Invoices not transmitted to ICEGATE because of Negative ledger balance.

Dear expertsm
One of client received following email. Client does not have any import-export business.How to resolve this? and what does this means.

This is with reference to the recent processing of export invoices for GSTIN 27AVDPP7241C1ZP. Please be informed that the invoices have failed validation at GST System, and haven't got transmitted to ICEGATE for further processing.

The GST System uses ledger based approach to validate if sum total of IGST/CESS paid under Table 3.1(b) of GSTR 3B across all periods is equal to, or greater than, the sum total of IGST/CESS from invoices under Tables 6A/9A/6B of GSTR 1 across all periods. The eligible invoices, having complete SB/Port details, are transmitted by the GST System only if such cumulative validation of IGST/CESS is successful.