Are you sure it is one of the actual towers ? All the towers in the large circle thing which has the teleporters and the final boss in it are not actually scout towers. The actual scout towers are past it and out a ways. I found that when I ran my Theurgist through that quest quest helper pointed me to those other towers that look the same but are not scout towers. That is the only reason I can think of. Sorry if this doesn't help.
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