I can't read previous Time Machine backup drive

[tommyhawk]

I filled up a 250gb My Book external drive using Time Machine. Replaced it with 500gb My Book and now can't read the old 250gb one when I reconnect it. My iMac doesn't recognize it. (I lost a large picture folder that is now only on the 250gb drive).
Any ideas?

 

[JediMeister]

Try another port, test with another USB/FireWire Device. See if the hard drive is receiving power correctly if its externally powered or powered through the USB 2.0 connection. Reset the SMC, try with another computer.