Can't exec a program from another

[STAN1ZX]

I have program "A" which when started sends an exec. to programs "B" and
"C".
Pgm B gets started but not pgm C.
I have all the permissions opened up as far as I can see, but it still does
not work.
I can click on pgm C at its location and it will start.
What or where can I look for something that might not be set ?
Thanks
Stan