Approving consolidated invoice

All,

Version: 6.3.1
Two standard invoices(one being XXX.20130815-0003) being consolidated into a single parent invoice. the invoices have been generated from the related matched buy shipments. When approving parent invoice for voucher generation, OTM gives the below error.

Could not approve invoice XXX.20130815-0005

ejb.VoucherInvoiceLineitemJoin records not found: sql=select j.invoice_gid, j.lineitem_seq_no, j.voucher_gid from voucher_invoice_lineitem_join j, voucher v where v.invoice_gid = ? and v.voucher_gid = j.voucher_gid, sqlValues=[XXX.20130815-0003]

Could not retrieve VOUCHER_INVOICE_LINEITEM_JOIN(s)


Any hint on how to fix this issue?

Regards,
Nikesh