Red Flashing Light after drive added

I have 4 (2TB) hard drives in my first generation Drobo and I got a Red Light indicating that I was almost out of storage and needed to add an additional drive. I purchased a 3 TB drive and replaced the top drive that was Red. Now I am getting a Red Flashing light. Does that mean that this drive is bad or is that normal while the drive is rebuilding. It is still blinking Red after 45 minutes.

did you put the latest firmware on before updating?[hr]
did you put the latest firmware on before updating?

I did not check to see if I have the latest. I have firmware version 1.3.7. Is there a newer version?

I did check and I do have the latest firmware. I thought I had purchased a bad drive so I returned it. I have just put in another brand (Hitachi) and I am having the same problem! Someone please advise.

first gen will never supprt 3tb from what i can see on their support site[hr]

Yes, thanks for your reply. I just got off the phone with support confirming what you just said. There is no support for the 3TB drives. Guess I will be biting the bullet and getting a Drobo S.