XI problem file to file scenario

Trying to send vendor from Java application to R/3. Now the process is source xml file is place in one directory of FTP and XI picks the file to transform the data After mapping the data to the target structure , XI is supposed to place the file back to another directory in FTP.

Currently when we place a xml file in the FTP directory , XI picks the file and processes the data but it is not putting the file back into another directory.

I see a successful message in SXMB_MONI. Checked the communication channels are activated .Tested MM and IM , they are good.

It did work earlier but now it doesn't work. What could possibly stop XI putting the file back another directory in FTP.