Calling dll from VBA and getting a big complex UDT as a return value - "bad calling convention" error.

I've a C dll (from the third company - so I can't change and recompile it) accessing a GIS-System database. This is not a COM dll - so the functions can be accessed from VBA only with "Declare". This dll has 6 functions, that have to be called in a logical order to get my query to GIS db "answered".

From the C header file the parts that seem to be relevant (I'm not a C programmer - so I may make a mistake), look as following:

1) UDT structures:

typedef struct SVersionsInfo
{
    char Version[6];
    char Zusatz[6];
    TDatum DatTabellen;
    char Beschreibung[256];
} TVersionsInfo;

// Attribute der Entitдt "GisRisiko":
typedef struct SGisRisiko
{
    char Sturm[2];
    char Erdsenkung[2];
    char Ueberschwemmung[2];
} TGisRisiko;

// Attribute der Entitдt "GisAbfrageParameter":
typedef struct SGisAbfrageParameter
{
    TBool befuelleTabellen;
    TBool KzRisikoKlassifizierung;
    TBool exakteSuche;
    char PLZ[7];
    char ID_PLZ[8];
    char Ort[51];
    char ID_Ort[8];
    char Strasse[51];
    char ID_Strasse[8];
    char Hausnummer[51];
    char ID_Hausnummer[8];
} TGisAbfrageParameter;

// Attribute der Entitдt "TGisDatenSet":
typedef struct SGisDatenSet
{
    TBool befuellt;
    //TBool gefunden;
    TBool eindeutig;
    short Status_PLZ;
    char ID_PLZ[8];
    short Status_Ort;
    char ID_Ort[8];
    short Status_Strasse;
    char ID_Strasse[8];
    short Status_Hausnummer;
    char ID_Hausnummer[8];
    TAlphanumListbox LbPLZ;
    TAlphanumListbox LbOrt;
    TAlphanumListbox LbStrasse;
    TAlphanumListbox LbHausnummer;
    TGisRisiko RisikoKlassifizierung;
} TGisDatenSet;

// Attribute der Entitдt "TGisAbfrage":
typedef struct SGisAbfrage
{
    TMeldung *Meldung;
    TVersionsInfo *VersionsInfo;
    TGisAbfrageParameter *GisAbfrageParameter;
    TGisDatenSet *GisDatenSet;
} TGisAbfrage;

// Boolean-Typ
typedef short TBool;                            // 19.01.98, S.J.
#ifndef SWIG
#define false   0                               // 19.01.98, S.J.
#define true    1                               // 19.01.98, S.J.
#endif

// Datum-Typ
typedef struct SDatum
{
    short           Jahr;
    unsigned short  Monat;
    unsigned short  Tag;
} TDatum;

// Wertepaar von zwei Zeichenketten
typedef struct SAlphanumWertepaar
{
    char    Schluessel[51]; // 18.12.97, S.J.
    char    Wert[51];
} TAlphanumWertepaar;

// Listbox mit alphanumerischem Schlьssel
typedef struct SAlphanumListbox
{
    short               Anzahl;
    TAlphanumWertepaar  *Werte;
    char                AktuellerSchluessel[51];    // 18.12.97, S.J.
} TAlphanumListbox;

// Definition der Ьbergabestruktur fьr Meldungen der DLLs
typedef struct SMeldung
{
    char    Typ;        // 18.12.97, S.J.
    short   Nummer;     // 18.12.97, S.J.
    char    Text[256];  // 15.06.98, S.J.
    char    Hilfe[51];  // 15.06.98, S.J.
} TMeldung;

2) exported functions (in the order of a usual call):

//Exportierte Funktionen
//
short API_EXPORT initGisAbfrage(char* PfadDLL, char *PfadDaten);

TGisAbfrage* API_EXPORT erzeugeAbfrageStruktur(void);

TBool API_EXPORT ausfuehrenAbfrage(TGisAbfrage*);

TBool API_EXPORT loescheAbfrage(TGisAbfrage*);

TBool API_EXPORT loescheAbfrageStruktur(TGisAbfrage*);

TBool API_EXPORT exitGisAbfrage(void);

----------------------------------------------------------------------------------------------------------------
In VBA the test module has the following code:

Public Type Bool
    Bool As Integer
End Type

Public Type Datum
    Jahr As Integer
    Monat As Integer
    Tag As Integer
End Type

Public Type AlphanumWertepaar
    Schluessel As String * 51
    Wert As String * 51
End Type

Public Type AlphanumListbox
    Anzahl As Integer
    Werte As AlphanumWertepaar
    AktuellerScluessel As String * 51
End Type

Public Type VersionsInfo
    Version As String * 6
    Zusatz As String * 6
    DatTabellen As Datum
    Beschreibung As String * 256
End Type

Public Type GisRisiko
    Sturm As String * 2
    Erdsenkung As String * 2
    Ueberschwemmung As String * 2
End Type

Public Type GisAbfrageParameter
    befuelleTabellen As Bool
    KzRisikoKlassifizierung As Bool
    exakteSuche As Bool
    PLZ As String * 7
    ID_PLZ As String * 8
    Ort As String * 51
    ID_Ort As String * 8
    Strasse As String * 51
    ID_Strasse As String * 8
    Hausnummer As String * 51
    ID_Hausnummer As String * 8
End Type

Public Type GisDatenSet
    befuellt As Bool
    eindeutig As Bool
    Status_PLZ As Integer
    ID_PLZ As String * 8
    Status_Ort As Integer
    ID_Ort As String * 8
    Status_Strasse As Integer
    ID_Strasse As String * 8
    Status_Hausnummer As Integer
    ID_Hausnummer As String * 8
    LbPLZ As AlphanumListbox
    LbOrt As AlphanumListbox
    LbStrasse As AlphanumListbox
    LbHausnummer As AlphanumListbox
    RisikoKlassifizierung As GisRisiko
End Type

Public Type Meldung
    Typ As Byte
    Nummer As Integer
    Text As String * 256
    Hilfe As String * 51
End Type

Public Type GisAbfrage
    Meldung As Meldung
    VersionsInfo As VersionsInfo
    GisAbfrageParameter As GisAbfrageParameter
    GisDatenSet As GisDatenSet
End Type

Const PfadDll As String = "d:\Gis"
Const PfadDaten As String = "d:\Gis\Daten"

Declare Function initGisAbfrage Lib "D:\Gis\GisAbfrage32.dll" (ByVal str1 As String, ByVal str2 As String) As Integer
Declare Function erzeugeAbfrageStruktur Lib "D:\Gis\GisAbfrage32.dll" () As GisAbfrage
Declare Function ausfuerenAbfrage Lib "D:\Gis\GisAbfrage32.dll" (GAbfrage As GisAbfrage) As Boolean
Declare Function loescheAbfrage Lib "D:\Gis\GisAbfrage32.dll" (GAbfrage As GisAbfrage) As Boolean
Declare Function loescheAbfrageStruktur Lib "D:\Gis\GisAbfrage32.dll" (GAbfrage As GisAbfrage) As Boolean
Declare Function exitGisAbfrage Lib "D:\Gis\GisAbfrage32.dll" () As Boolean

Sub test()

Dim intResult As Integer
Dim GAbfrage As GisAbfrage

Dim blnTmp As Boolean
Dim intTmp As Integer
Dim lngTmp As Long

Const sProcSig As String = MODULE_NAME & "test"
   
On Error GoTo PROC_ERR
    intResult = RESULT_OK

    intTmp = initGisAbfrage(PfadDll, PfadDaten)
    GAbfrage = erzeugeAbfrageStruktur()
    blnTmp = ausfuerenAbfrage(GAbfrage)
    blnTmp = loescheAbfrage(GAbfrage)
    blnTmp = loescheAbfrageStruktur(GAbfrage)
    blnTmp = exitGisAbfrage()
   

PROC_EXIT:
    Exit Sub
   
PROC_ERR:
    intResult = RESULT_ERROR
    If errTypeReport(sProcSig) <> Critical Then Resume Next
    Resume PROC_EXIT
    'Resume
End Sub
--------------------------------------------------------------------------------------------------------------------

I get an error "bad calling convention", Nr. 49 for this line:

    GAbfrage = erzeugeAbfrageStruktur()

and think, that the UDT, that is to be created with erzeugeAbfrageStruktur() in C dll differs from the UDT I've tried to mirror in VBA module. The UDT GAbfrage has a complex structure (appr. 60 primitive variables, differently grouped). How can I make the test function run?

Some colleague of mine had made this dll work for Java programm, but for mapping the UDT from C to Java they used "SWIG" tool (http://www.swig.org). I haven't found smth similar to map the structure to VB-VBA.
I assume that the order and the variables type in my UDT are the keys, but how to check the conformity of allocated memory in C and in VBA? Are there some special tools? As the UDT is big and complex, I can't test it part by part (or just don't know, how to test it by parts :( ). The function runs or doesn't run and to have it run, I have to have the whole UDT correct.

So, please help.