Why won't my Droid X recognize my replacement battery?

[AC Question]

my droid x wont recognize my replacement battery

I have a spare battery which is the same make, model and manufact. as original battery. yet I get a question mark in the battery icon

 

[B. Diddy]

Welcome to Android Central! Where did you buy it? Batteries may be defective or counterfeit. Have you also let it charge on a wall outlet for at least 4 hrs undisturbed?