Debit note

Taxable invoice is wrongly raised as Exempted invoice. Next month found and raised Debit Note for the GST Amount.

In Debit Note in GSTR1,I enter the Debit Note amount. If the Taxable amount is entered than only the correct GST amount appear in the Return. If I enter the Taxable amount, then GST amount is coming correctly. But getting error message "Processed with Error".

Please tell me how to enter Debit Note for the GST amount for the Taxable amount wrongly invoice raised Exempted invoice. 

Thank you