Why will not Time Machine work?

I Recently changed the HD on my 2009 iMac as it was running out of space. But when I came to restore the data from Time Machine the Mac refused to read it. I tried replacing the old HD and making new copies on TM and then putting the new HD in situ with the same result.

I then tried to use Migration Assistant but this also refused to recognise the TM as a source.

I Am able to enter TM when using the original HD so why will it not work with the new one?