File FTP Sender Channel not picking up file using wildcard

I have configured File FTP Sender channel. I have a file on FTP server called expense_dM.

In my sender channel configuration the file name I have specified is expense_d*

Polling is set to 60 seconds and connection mode is permanent.

When I activate it it is able to pick up the file on the ftp server immediately. However any subsequent files that are placed on the ftp server are not picked up.

File authorization is not an issue because if I stop the channel and start it up again via the RWB it is able to pick up the file.