Case law-vat input tax claim

Inadevertently input tax not claimed an amount of 2 lakhs while filing the VAT 200 return under APVAT act in 2011-12, We came to know ITC not claimed while VAT assessment in last month, We have given the reply to department for allow ITC which is not claimed, Department is asking provide any case law as ITC can clam at the time of Assessment eventhough ITC not claimed while filing VAT return, then only they will consider our request.You are requested to provide any case law in respect of inadvertently input tax not claimed while filing VAT return and ITC can claim Assessment itself under APVAT act or any other act.

Thanks in advance & waiting for your valuable reply.