Adding data in column to a cell

Okay, I think this is probably easy, but I can't figure it out. Half the problem is that I'm not entirely sure how to phrase it.

What I want to do is to take a number of items in a column and put them in a cell, belonging to a certain ID.

So, the data looks like this:

ID Cert
10056 MS1
10056 MS3
10056 MS2

I want the finished product to look like this:

ID Cert
10056 MS1;MS3;MS2

The order of the certs doesn't matter.

Okay, so that works on the test sheet, but when I input it with real values, I get a #VALUE! error.

The difference is the ID's are something like
RLP300500

And the certs are like:

Certified Microsoft Fundamental person

Actually, I think I found a work around.