VPI Aries 2 platter is creating hum

My new Aries 2 platter is creating hum. Thought it was a grounding issue to begin with. But, when all efforts failed to eliminate it, I re-installed my original platter once again. Dead quiet. Has anyone else experienced this? Curious as to the cause of this problem.
What materials are the original platter made from? It could be that the old platter was shielding the cart from the TT motor or some other source of electronic hum and that the new acrylic platter isn't providing the same shielding.

Just a guess, but I've found that my Rega table hums--with volume cranked all the way and needle above the record--when it is located above my amp. Moving it to a table beside the amp eliminated the hum completely, so it was definitely not motor hum in my case.
Hi cbrentc, not really sure what material(s) the original was made from. It looks like solid steel. I tried extra grounding on the platter,tonearm and motor with no success. Hum occurred when cartridge met record only. I have my class A amps on either side of the table about 6" apart. Even though the motor is not attached to the table can it induce hum?
You might be able to play with a sheet of aluminum foil to see if you are getting electromagnetic interference from somewhere, it should act as a barrier to the em source. FWIW, made the same upgrade & did not get any ill effects.
Just call Harry Weisfeld at VPI. The office is open Tuesday thru Thursday 9 to 5. I had a problem a while back, called Harry and he talked me through it. Problem solved.
Thanks for the responses so far. Have e-mailed VPI. Jeff_jones, will play with the aluminum foil. May I ask what differences you heard with the upgraded platter? For the short time the new platter was on, it appeared to produce clearer detail but wasn't as smooth and musical. Probably something that can be resolved by adjustments.
The original platter is a mixture of stainless, acrylic, cork and lead.

I trust that the new acrylic platter and bearing are better sonically, but think that the white-ish acrylic destroys the look of the table (the new platter looks like the afterthought that it is).
Byfo - Haven't got your email yet. But anyway the answer is that I bought & installed the platter, ring clamp, and a new cartridge all at the same time. Ended up with a better sound but I can't estimate the effect of individual components.
I don't know what would cause hum under those circumstances. Please update if you solve the problem--inquiring minds, etc.

Tried installing platter again. Hum still present. Played around with grounding and foil once again but didn't solve problem. Re-installed my old platter ( the noise floor is absolutely quiet) and will leave. I'm not willing to move components to solve this problem. The sound is good enough.