Directx9.0c errorFollow

So i was thinking about joining and found the Trial of the Isles demo, so i go to try to play and i get an error saying i need to install Directx9.0c. The problem is, its already installed, i have an nVidia Geforce FX 5500 which is DX9 compatible (being as it comes with the video card) it has pixel shaders because ive played plenty of other games that needed DX9 and pixel shaders with no problems. Anyone know whats up? I'm pretty sure the full game wont run if the demo wont even run