found the root cause-
we have emulation parameter 'Enable RFID' as YES and also we have the above script that enables it when session connects.
so these 2 settings are overlapping eachother and failing to activate it.
so, I put a delay of 10sec before starting the script and the problem solved.
Script( RFID_Scanner_Auto_Enable )
Activate( Connection )
Delay( 10000 )
Escape_Sequence( "$1;1R" )
Return