Can't install totalspaces2 - unapproved caller

I’m trying to install TotalSpaces2 (trial, downloaded today) and I get the following error message after I accept the terms, confirm the disk/destination, and press install. I have 7.5GB space remaining on my drive and I’m running 10.9.4 with admin privileges.

Unapproved Caller
SecurityAgent may only be invoke by apple software.


Hi, I’ve not seen this message before.

I just googled it (“SecurityAgent may only be invoked by Apple Software”) and it seems most answers mention that there may be some hard disk or hardware problem.

I think it could also be a corrupt download of TotalSpaces2. Perhaps, as a start, download the app again?