Mid function hook

hi
iam having a little problem
iam trying to make an undetected d3d hack
i used mid function hook and it worked fine (on my win xp)

but when i tried it on win7 cf crashed because of function changes
(i hooked VTABLE [42] + 0x13 on my win xp and a command starts from
VTABLE [42] + 0x12 on win7 so the function is completely fucked up)

can any one help me to hook mid function on any version of windows??

Mid-function hooking on Win7 is different then xp..

Vtable42 = endscene right?

endscene is always VTable42
but the function body is different so when i test it in xp it works
but doesn't work on 7