I have Lightroom 6.2.1which is not a CC version. I have attempted to update to 6.3 in the past and receive an error code - U44M2P28 and says the update can't be completed. When I start Lightroom and go to Help > Updates, I get the message that I have the latest version of the software. I want to update to 6.4, but can't. When I tried, I got the same error code and message. What do I do next?