Follow these steps.
Look guys, and in case no one has noticed, which apperantly alot of you haven't, SP2 included a new security feature thats stop's applications or registry entries from being merged and alot of developers haven't updated their readme's, it's no secret and a pretty easy fix, if your running service pack 2 you'll need to right click on the key you receive from slysoft or element 5 and then goto properties look at the bottom you'll see a button to "unblock" the file, this will remove the problem of getting the key to properly merge. Either by double clicking and mergeing or right click and merge.
If your running service pack 2 you will have to do this to rar, zip, reg, bat or any other file XP SP2 deems is a threat.
There are way too many threads about this key problem don't ya think?