field length problem

Hi

my source side field posex is of length 6 while reciever field po_item is of length 5,in map test it is working fine,but running the interface the entire 6 digits are getting picked up from source though we are giving 5 digits only,the reason might be is sender is sap field so by default 0 is getting prefixed for 5digits

ex: source(posex(6)) target(po_item(5))

00010 00001

but i should get target as 00010

both sender and reciever are sap systems

so how could i solve this issue.

regards

raghu