I don't know what code you're using, but there are two sfx codes
For .BNK Files.
For Sawnd Files
I know they look alike, but believe me they're different. The Sawnd File Code is more longer than the BNK file code.
I think the one you're using is for Sawnd files
If you got the code from here, it's not going to work since it's only for sawnd files
http://forums.kc-mm.com/index.php?topic=61460.0If you got it from here, it will work , because this is for bnk files.
http://forums.kc-mm.com/index.php?topic=61461.0