Michael:

The file not found is very common when you try to access program outside of visual foxpro and inside also. Be sure that you path is correct.

using "set default to (mynewpath)" then issue the "set default to (myoldpath)" after you are ready to return to the application that make the call.

I use the sys(2003) to assign my old path to my variable "myoldpath" and then recover my old path when return to my aplication.

Also try to debug the in what path are you at the moment you call the external procedure and validate the path in your external procedure to verify that you are trying to look for the file in the incorrect place.

Good Luck!!