H5Tcopy and DLL library

I am accessing the DLL library, and most functions work great, i.e., passing back and forth integers, arrays, and strings.

However, H5Tcopy[arg] does not work for an integer argument. It returns -1. The idea of the integer argument is that it represents something like H5T_NATIVE_INT. Since I am calling the DLL directly, I need to supply an integer argument instead of the symbol.

I can use H5Tcopy[arg] successfully when the argument represents a dataTypeID obtained from H5Dopen[...].

I guess the problem must be that H5T_NATIVE_INT represents a pointer to an object when the C code is compiled, rather than just an integer. But when calling the DLL library externally when all I can pass is an integer, how can I make H5Tcopy[...] work with H5T_NATIVE_INT? What argument should I pass to H5Tcopy[...]?