Freecom 400gb Drive

I had a Freecom 400gb Hard drive running but it was getting close to its capacity, to solve this problem I purchased another 400gb drive.

I installed the Freecom software for the second time (I had initially installed it when I purchsed my first external drive.)

My computer briefly recognised that I now had two external drives. However, whenever I now turn on the computer it recognises one of the drives (the first one I installed) but not the second.

Is there anything I should have done but didn't do?

I look forward to your replies