Regarding gstr 3b return

SIR

             WE HAVE EXCESS CREDIT OF GST AFTER FILLING TRANS-1. BUT SIR IN GSTR 3B HE CAN NOT SHOW EXCESS CREDIT. SUPPOSE WE HAVE LIABILITY OF IGST IS 50K AND WE HAVE CREDIT OF IGST IS 100K. THEN WHEN I GO THROUGH PAYMENT THOROUGH ITC THEN WHEN I ENTERED 100K . THEN SERVER ARE SAYING THAT YOU CAN PUT ONLY 50K.THEN SIR HOW MY BALANCE 50K IGST WILL SHOWING IN 3B. THANKS