Help me with this error when compiling

I'm making a simple hack I want to release and I need help. When ever I build my hack it says
fatal error c1083: Cannot not open include file: 'd3dx9math.h': No such file or directory.
And I already added the file in my source.

this kind of stuff belongs in the source code section

the help section(what u posted this in) is ment for help usings hacks that have been released

plzz move to source code section

these are the rules for the help section

Posting errors you receive while playing CA
Asking for help when CA is crashing
Posting errors you get when using hacks



what he is asking doesnt fall into any of these categories so it doesnt belong here
he needs help compiling a hack and he would get better help if this was posted in the source code section