but since _data != NULL, the function does not return CheatDetectedBooom!
And why would you write <addy> to 0x90? What's so important about that address?
Revised your code for you (consider it a favor)
I bet you're just some alteriw admin troll who doesn't even know how memcpy works.
memcpy((LPVOID)0x90, (LPVOID)<addy>, sizeof(PBYTE));
This is probably what you meant:
BYTE _data = 0x90;
memcpy((LPVOID)<addy>, &_data, sizeof(_data));
// 0x90 != 0, so why not comment out this section?
if(_data == NULL)