Double check that you dont have a second folder in your current "sounds" folder also labeled "sounds", for some reason this happens to me every time I install a new soundpack. If it is, just copy the contents of the second folder and paste them over the other one, then delete the sounds/sounds folder.
Even if you have the new stuff in a secondary folder inside the main folder, it will continue to use the old stuff instead of the new.
I know it sounds complicated, but I really dunno how to explain it more clearly.
Try to explain better though...
You may have a filepath something like c:/program flies/htc/aceshighII/sounds/sounds. You want to copy the second sound folders contents and paste them into the first, then delete the second (after making sure you have a backup someplace just in case).
If that still doesn't work, then you have a different problem than I did, but I figured it was worth a try.