Can't compile with _strspnp()

I can't compile an application when I use _strspnp even if I include tchar.h. Can someone help me?
Thanks.

Well, this seems to compile fine (VC6, SP2):

const unsigned char* p1 = (const unsigned char*)"String1";
const unsigned char* p2 = (const unsigned char*)"String2";
unsigned char* ptr = _mbsspnp( p1, p2 );