pinvoke c dll callback function?

Hi,

I've got a third party c dll that I'm trying to make function calls to from c#.  I'm using pinvoke to do this, but I'm new to c#, so I'm not sure if I'm doing this right.  One of the function calls from c# passes a callback function to and i'm not sure how to implement this.  Here's the code

[c]
//QueAPI.dll

typedef uint16 QueErrT16; enum
    {
    queErrNone    = 0,              /* Success                                       */
    queErrNotOpen = 1,           /* Close() without having called open() first    */
    queErrBadArg,                   /* Invalid parameter passed to function          */
    queErrMemory,                   /* Out of memory                                 */
    queErrNoData,                   /* No data available                             */
    queErrAlreadyOpen,              /* The Que API is already open                   */
    queErrInvalidVersion,           /* The Que API is an incompatable version        */
    queErrComm,                     /* There was an error communicating with the API */
    queErrCmndUnavail,              /* The command is unavaialbe                     */
    queErrStillOpen,                /* Library is still open                         */
    queErrFail,                     /* General failure                               */
    queErrCancel                    /* Action cancelled by user                      */
    };

typedef uint8 QueNotificationT8; enum
    {
    queLocationChange       = 0,    /* The GPS position has changed                 */
    queStatusChange         = 1,    /* The GPS status has changed                   */
    queLostFix              = 2,    /* The quality of the GPS position computation
                                        has become less than two dimensional        */
    queSatDataChange        = 3,    /* The GPS satellite data has changed           */
    queModeChange           = 4,    /* The GPS mode has changed                     */
    queEvent                = 5,    /* An event has occurred (i.e. sunrise/set,
                                       route has started/ended, etc. )              */
    queCPOPositionChange    = 6,    /* The GPS CPO position data has been updated   */
    queSatelliteInstChange  = 7,    /* THe GPS CPO satellite data has been updated  */

    queUserNotificationCount,       /* Count of change type enumerations(user only) */

    // Internal notifications (do not publish, not visible to end user)
    quePickPointComplete,       /* The user has picked a position.              */
    queNotificationCount,       /* Count of change type enumerations (all)      */

    queInvalid              = 0xFF, /* Invalid message. Ignore                      */
    };

typedef void (__stdcall* QueNotificationCallback)( QueNotificationT8 );

__declspec(dllexport) QueErrT16 QueAPIOpen( QueNotificationCallback callback );


[c#]
//QueAPI.cs

public enum QueErrT16
{
      queErrNone    = 0,              /* Success                                       */
      queErrNotOpen = 1,            /* Close() without having called open() first    */
      queErrBadArg,                   /* Invalid parameter passed to function          */
      queErrMemory,                   /* Out of memory                                 */
      queErrNoData,                   /* No data available                             */
      queErrAlreadyOpen,              /* The Que API is already open                   */
      queErrInvalidVersion,           /* The Que API is an incompatable version        */
      queErrComm,                     /* There was an error communicating with the API */
      queErrCmndUnavail,              /* The command is unavaialbe                     */
      queErrStillOpen,                /* Library is still open                         */
      queErrFail,                     /* General failure                               */
      queErrCancel                    /* Action cancelled by user                      */
}

public enum QueNotificationT8 : byte
{
      queLocationChange       = 0,    /* The GPS position has changed                 */
      queStatusChange         = 1,    /* The GPS status has changed                   */
      queLostFix              = 2,    /* The quality of the GPS position computation
                        has become less than two dimensional        */
      queSatDataChange        = 3,    /* The GPS satellite data has changed           */
      queModeChange           = 4,    /* The GPS mode has changed                     */
      queEvent                = 5,    /* An event has occurred (i.e. sunrise/set,
                  route has started/ended, etc. )              */
      queCPOPositionChange    = 6,    /* The GPS CPO position data has been updated   */
      queSatelliteInstChange  = 7,    /* THe GPS CPO satellite data has been updated  */

      queUserNotificationCount,       /* Count of change type enumerations(user only) */

      // Internal notifications (do not publish, not visible to end user)
      quePickPointComplete,       /* The user has picked a position.              */
      queNotificationCount,       /* Count of change type enumerations (all)      */

      queInvalid              = 0xFF, /* Invalid message. Ignore                      */
}

//I don't know how to implement the call back function that QueNotificationCallback would call here.

[DllImport("QueAPI.dll")]
public static extern QueErrT16 QueAPIOpen(QueNotificationCallback callback);



So that's the code I'm working with.  The QueAPIOpen function is what I'm trying to call from c# to the c dll.

Thanks