computer not reading new memory card?

[bbe1367]

ok, at first my vibrant was working just fine with my computer, i was avaible to swap pictures, music and everything between the 2...but now i took out my memory card from my old hd2 and put it in(hence its 16gb, and i didnt even use my hd2 for a day it was given to me so it has nothing crazy on it) and now when i plug in my vibrant, it dosent read the card for some reason, removable drive pops up, but it wont access it, i also saw this happen with someone elses vibrant, any advice?...and oh yea, i do press mount on the usb thing on the vibrant screen.

 

[PlowRox]

Did you format it?

 

[bbe1367]

format how