Failed to load PDF document.

when client using browser to generating pdfs file directly from pool members are fine but it is failed tp load PDF document if client generating the same pdfs file using VS (BIG-IP LTM) even we try to set up the pass through VS (performance layer 4), it is still failed to load PDF document. Note that the path directly to pool members or VS from Client's browser is the same.

Any help i'm appreciated.

thanks in advance.