I thought I'd post this in case any of you are having problems. I recently lost both of my keys and fobs (I think they were taken), so I had to get a new key and ordered two used fobs on EBay.
The replacement key was cut at my local Isuzu/Suzuki dealership for $25 from the VIN. I had to take proof of identification and the title with me and they cut one from the VIN. It was a little stiff but a light scuffing with 220-grit sandpaper and it works well.
The replacement fobs came and I programed them per the Isuzu Service Manual. Everything went fine, but BOTH fobs would only lock the doors, not unlock and not panic. I figured I had either the wrong fobs or something else was the problem.
Fast forward to day, I put in new batteries in both fobs (CR 2016) and they both work like they should.
SO, short story made long, if you have problems with partial fob funcitionality, replace the batteries.