I had this problem too, but I found that adding the activation keys directly to elicenser then downloading the license for each new sample set meant that when going back to the download manager, everything worked a treat.
It seems that saying (install) from download manger should only be done once you have activated the new sampleset first.
If you don't do it this way, it tries to license the sampleset, but fails, giving the wrong reason !
Norman
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