Volvo Cummins ISX Eaton Automatic Gear won't change

I have 2005 Volvo VNL670 with Cummins ISX 400 and Eaton Fuller 10 Speed Automatic. From last week it started having gear changing issue. If i drive on Auto D- it wont shift as it used to and on 7th gear it will throw up the truck then I have to put it in manual to either higher or lower gear. When I stopped end of trip it wont even fall into N . It was blinking N then unsuccessfully I tried several times to get in N and turned off but since then it wont even start, only - -. I towed it to a mechanic here. He could not find the issue with the gear hooking up on computer as there was no code but it still having the gear changing issue in automatic/D. Please help. Thanks