Availability check issue

HI experts,

I created one stock transfer purchase order with availability check active.

unresticted stock quantity is 100 in mmbe & MD04. But agianst this po system not allow me to do PGI

& Commitmenet quantity in delivery schedule (po) is 25 . So there is deficit of

25 quantity . So How I get this additional 25 quantity in purchase order ?

I Search & use v_v2,CO06 but not successful . so please suggest.