trigger on file after remote ftp

My problem:

A file called  FL55AFL comes from the remote machine via FTP.
The command there is

PUT SANTOSH/TRGTEST.TRGTEST               QGPL/FL55AFL.FL55AFL

this works fine everytime i run it and the file gets changed at the local
machine.

Now i have added a trigger on the file FL55AFL for an after/insert.
This trigger will call a CL and a COBOL program. THe cobol program does
some calculations after that.

After this i again ftp from remote nachine with the fol command..
PUT SANTOSH/TRGTEST.TRGTEST               QGPL/FL55AFL.FL55AFL

this results in failure of ftp with the fol error mesg.

 put santosh/trgtest.trgtest  fl55afl
 227 Entering Passive Mode (89,0,0,16,20,78).
 150 Sending file to member FL55AFL in file FL55AFL in library QGPL.
 426-Cannot write to member FL55AFL in file FL55AFL in library QGPL.
 426 Data transfer ended.
  Message . . . . :   426-Cannot write to member FL55AFL in file FL55AFL in
   library QGPL.

Now when i go to the local machine and check the file, it has no members
while before ftp , it had 1 member .

Apparantly, when the ftp was executed , it seems that it deletes the
existing member and creates a new one.
While the member was deleted during ftp , it was not created successfully.

If I remove the trigger, the thing starts working.

My requirement is very simple :
Whenever a particular file comes to my machine, i should be able to run a
program.
For this, i can think of 3 ways :

1, The way i mentioned as above . but i got stuck.
2. Can we monitor the change date and time of a particular file
continously. Whenever it is updated , the required cobol program will run.

3. From the remote system , after the ftp , we  send a message  thru socket
programs which when recieved here will fire the cobol application. This
options is always used in my company and a third party product runs here
just like the MQ Series.

But my contention is why isnt the first option working?
why is the trigger preventing in creation of a member during ftp.

Are there some options to be given in the ftp   command which will make it
happen???

I hope u all go the right picture of my problem,

Santosh.


Signature......................

e- mail at :  santoshp@lot.tatasteel.com
ITS, Tata Steel.
Jamshedpur, India.
Tel : 842134 (O) , 200279 (R).