well, i have the same problem , but i got the solution.
1. open MHS
2. Menu File/Open debug; and browse to engine.exe in nexon folder
3. click in ok
PD. in will open the anticheat program and then 2 windows click ok in both
4. in the MHS in the title will say "waiting on engine.exe"
5. Now open combat arms.
6. start hacking
PD. sorry for the grammar mistakes,i'm from mexico