payment block in invoice verification

I am using GR based Invoice Verification.

I create a po for 100 quantity

I receive GR 50 quantity

Invoice verification quantity 100

my IV goes on blocked invoice.

but when I go back to the Invoice verification mode in display mode, it still shows the payment block as free for payment

but i want it to show payment block - Invoice verification.

How does the system automatically do this?where is the configuration for this

Regards,

Anu