Problem with input statement on HP

We are in the process of porting our Informix applications from a 3B2 to a HP9000/750. After recompiling one of our data entry applications, we experienced a problem on the HP which we have been unable to resolve. When the user chooses to query the status of a shipment, the function called opens a form, then uses an input statement "input vship.gbl_no from aship.gbl_no" to prompt for the shipment ID. The attributes for this ID in the form file are: f01=aship.gbl_no, required, upshift, picture = "A-#######-##". On the HP, the first character input for the shipment ID does not display in the form field position, but is displayed in the upper left corner of the screen (position 0,0). Subsequent characters are displayed properly. Instructions to display the shipment ID variable to the form field work properly. The problem only seems to occur in the input statement. If we eliminate the PICTURE attribute in the form, the problem does not occur. The problem occurs on dumb terminals directly connected to the HP9000/750 and on X-terminals accessing it via LAN. While I could eliminate the picture from the form and build the edit into my 4gl source, I don't like unsolved mysteries on computers. Unfortunately, with the government's lightning speed in procurement we are probably months away from having our Informix maintenance contract renewed so I can't call them for support. Any ideas what could be causing this problem?