Dunning letter does not have any transactions

We are facing a peculiar situation where dunning letter is generated but it has only body of the letter and no transactions. Any idea what could be wrong. Normally, program ends with error if there are no transactions to display but this issue seems to be different. We are getting the output on email as well, so all seems to be well on email delivery of letter. Also, delinquent transactions are available in Collections work area.