The problem is that you aren't developing on the target machine. (That is to say, the computer of the consumer, who runs your program)
What you need to do is include the DirectX 9.0c Redistributable package with your program, so that they will certainly have all the right files.
You can download the package here:
http://www.microsoft.com/downloads/details.aspx?familyid=9226A611-62FE-4F61-ABA1-914185249413&displaylang=en
Then you just include that, and have them install it before using your program.
My site, for various stuff that I make.