XBee Pro configuration help (Error setting MY)

Hello, I was unable to find any help regarding my issue setting up my XBee Pro via AT commands. This is the module I have:

XBee Pro from Digi International. On the front it shows XBee Pro and shows S1.

The model is: XBP24-DMCIT-250 revF

I have two of these modules and I'm trying to set them up to communicate in a point-to-point fashion. When I attempt to set the MY via: +++ ATMY1000

I get an ERROR.

I'm fairly new to wireless communication and I would like to ask the community for some help. Most of the guides I have come across require the MY to be set along with the Pan ID and the DL. Can anyone get me started on basic point-to-point communication with the modules I have?

When I attempt to set the MY via: +++ ATMY1000

Where? How?

I get an ERROR.

Which one?