SSh/Interrupt key

Hi All

I'm having problems with ssh/putty/interrupt key.

During the search of the database, the user needs to cancel the search
I have a progress bar form with interrupt button in it. This is my form
code:
SCHEMA FORMONLY
LAYOUT (TEXT="Searching......")
GROUP
VBOX
GRID
{
[LBLprogress|pb                          ]

[sline                                   ]
                  [i]
}
END -- GRID
END -- VBOX
END -- GROUP
END -- LAYOUT
ATTRIBUTES
LABEL sline    = FORMONLY.status_line;
PROGRESSBAR pb = FORMONLY.progress_bar,VALUEMIN=1,VALUEMAX=100;
LABEL LBLprogress : TEXT="Progress",     JUSTIFY=RIGHT;
BUTTON i:interrupt, TEXT="Cancel", IMAGE="cancel";
END

I have this set in the program:
     DEFER INTERRUPT
     OPTIONS SQL INTERRUPT ON
     LET INT_FLAG = FALSE

I have this check after the SQL statement
     IF INT_FLAG THEN
      DISPLAY "Query was interrupted by user"
     END IF

When the user clicks on the cancel button as many times as they can, the
interrupt key is not working. Further more this operation is working
fine with rlogin.

I did echo the SSH_TTY and SHELL and they are set during the ssh login.
Note: we use ssh port forwarding option..

Any idea?

Thanks Kindly,
Ahmed Ali