Cenvat credit not availed in ER1 return for june 2017

The registered person must give details of sales of such goods in the FORM GST TRAN-1 at the end of each month during which the scheme is in operation. The amount of credit allowed will be credited to the electronic credit ledger maintained in the FORM GST PMT-2 on the Common Portal.
Defend your case as this is of transit period of VAT to GST.