Umm, dumb question time.
Does your CTRL key actually work?
These strings do work:
[Cmd192]
Name=Dive
Ctxt=1
Str=1030
Key1=0x44,c,"Ctl+D"
[Cmd193]
Name=Surface
Ctxt=1
Str=1031
Key1=0x53,c,"Ctl+S"
Next time you can check, try the other CTRL combos in game aka CTRL+Del or CTRL+Ins to fully raise lower the Obs scope.