freight vendor

Dear All,

I have created one imported purchase order , after i want to change the vendoer number in import condition like JCDB, JECV.. i am selecting the condition and click the lense icon , the vendor field is gred , the system doesn't allowed to change the vendor number . this is for production server only , i am able to change the vendor in quality . colud you please teel me which problem is there.

Regt,

kt.