Application over-rides driver. Things can't be random with computers, you just haven't so far been able to discover the cause.
With pdf files, the usual cause is Choose Paper source by pdf page size. No matter what you put in the driver, it won't matter if that is enabled.
MS Office products do it as well. Default tray (Automatically Select), which will choose whatever tray has the highest priority (Completely un-related to the stock you want), the Automatically Select option typically works correct with most brands of printer
To place proper blame, save the job as pdf and import into CWS5 and set it up that way, no chance for a misconfigured driver or application over-ride.
Sometimes after I try to print a pdf file from tray 5(bypass) I get an error message telling me to put paper in tray 1(or 3) or that the paper in tray 1(or 3) is not of the same size as the one that I specified on the computer(which makes sense because im trying to print from tray 5). This happens after i specify the properties on the computer and i put the paper in tray 5(the machine is a versant 80 by the way). This error is shown both in the command workstation and the machine screen. Now I could move the paper to tray 1(or 3) but I feel like I should give the orders to the machine not the other way around (plus then I have to move the paper I removed back in place). So far this happens randomly restart or praying dosn't solve the issue so any help or suggestion will be a appreciated.