dBase error codes

I'm having a problem with converting a codebase database file to a dBase file ( at lease I think it is a dBase file). I'm converting the file on a windows PC and transfering the converted file to a DOS based handheld. When the file is accessed the program crashes with the following error:

Fatal error 347
dBase Driver error

Does anybody know what this means?
Also any information on how to make sure I'm creating the header information of the dBase file correctly would be rewarded. I'm not sure how to calculate the record length.

Here is my header code:
                StringCopy(m_header.sig, "JUNI", 4);
            m_header.dver = 0;
            m_header.fver = 1;
            StringCopy(m_header.hres, "", 20);
            m_header.numberFree = 0;
            m_header.recNum = 0;
            m_header.numRec = (short)numRecords;
            m_header.numFld = 11;
            m_header.recLen = 26;  // NOT SURE HOW THIS NUMBER IS CALCULATED.
            m_header.fldNum = 0;
            tempFile.Write(&m_header, sizeof(header_struct));

Thanks.