Macbook Pro Mid-2009: Firewire still not recognizing devices after SMC and VRAM reset

I have reset the SMC and VRAM on my mid-2009 Macbook Pro, and the firewire is still not recognizing devices. I have tested an audio interface and external HD, both of which work on other computers. I cannot locate a thread that has any suggestions other than resetting the SMC and VRAM, which have not resolved the problem. If anyone has a solution, or can direct me to where I can find it, I would appreciate it very much.