P4210 - Processing options to backorder

I am working on an interface from DSI.  My interface will pick an order and advance it to ship confirm status - going from status 545 to status 560.  There will be times when we will pick short and will want the line to split so that part of the line will get picked and the rest of the line will backorder.  In my processing options for P4205, I have processing option 3 set to 1 on the Process tab (Backorder or Cancel).  When I run the script, it always cancels the line instead of backordering it.

I have a similar script set up but the difference is that the other script moves the status from 545 to 550.  That script successfully splits the line and backorders the remaining amount.  I've compared the processing options between the 2 versions and the only difference is the status code setting (545 vs. 560 on the Defaults tab).