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Hi,
There are problems currently with installing service packs for AC 2013 on both operating systems - 10.9 and 10.10. You can read more in these topics:
http://forums.autodesk.com/t5/autocad-for-mac-general/autocad-lt-2013-yosemite-trouble-re-install/td...and
http://forums.autodesk.com/t5/autocad-for-mac-general/sp3-bricked-autocad-lt-2013-for-mac/td-p/54558...So, I think you need to wait until Autodesk will solve this problems.
Maxim
