Balnket Update PO - is not working properly

 Hi ALL,

I have a requirement where I will be importing Blanket PO details to PO interface table .

my program is working fine and and PO are also successfully get imported to Base through 'Import price catalog' program , however when I am importing UPdate PO

its actually importing successfully bt doesn't update few Attribute columns . Also The PO version number reamins same . Normally whenever we change the Price column of a blanket PO,

PO revision number will get incremented , but in my case , it is not happening

Thanks

Vijay