__int64 is an intrinsic type. Its like char, int, long etc., which are automatically understood by the compiler and are not really defined anywhere in a header file. We use Microsoft's mktyplib tool to generate the type library for us from an ODL file. Apparently, ODL does not support the use of int64 (since VB 6.0 does not have a int64 data type) and hence the unknown type errors.
If you really need a type library, you might be better off working with a double or an unsigned int. This would be useful especially if you are planning to call your instrument from VB 6.0 and VB 6.0 does not have a int64 type.
Hope this helps
Bilal Durrani
NI
Bilal Durrani
NI