Thanks again to everyone for the help.
I upgraded the TIU to 6.1. If I remember right, I had to use the USB port to do that so I'm hoping it's not defective. I'll have to figure out what a USB/serial adapter is. Got back home to layout #1 and noted that the WIU is v.1.0. Haven't tried swapping out equipment yet in an attempt to isolate the problem but everything worked perfectly with WIU v.1.0 with both iPhones. I'm going to try hard to figure this out as I can't be the only one who has had this problem.
Ed