Transponder Codes do not match?

1. Receive ATC clearance.

2. Set my transponder to the assigned code in the Radio Stack.

3. In my Reality XP GNS GMAGTX display, the numbers never match the same setting even though everything seems to work fine. ATC acknowledges my setting as correct.

Is this the nature of the beast, or does someone know what causes this with a possible solution?

I posted this on the Reality XP forum, but never got a reply. In all honesty I butchered the post so badly I don't blame anyone who read it. Don't know where my mind was. Hopefully I thought it might get more exposure here.

Respectfully:

RTH