The frequency and step programs in by hand (154.1825 step 7.5), the issue is with Butel software. If it is just the one frequency, program it in by hand.
Note: you need to change the step for that channel FIRST, then reprogram the frequency. Otherwise the scanner sees the step as 5 or 12.5 and keeps correcting you. I would guess the Butel software may have the same problem.
If you really need to use the software, try this:
setup, software options, bandplan.
uncheck all the boxes and try again.
Another work around would be to program the entire bank with a freq that has steps common to all the presets (5, 7.5, 12.5, 25) with the step you choose. Example 154.4000 step 7.5 Then when you over write it, the step is already at 7.5 and the freq should go in OK.
I stopped using ARC products because of too many issues on too many products. I liked them but too frustrating.
The ARC780 yahoo group had several discussions on this.