Even though I have the Android SDK installed, I get "Error building Player: ArgumentException: An empty file name is not valid." when building

I’m running Mac OS 10.7.5 and Unity 3.5.7f6 with an iPhone and Android license. Unity seems to be unable to use the Android SDK, even though it’s installed, on my path, and the ANDROID_HOME env. variable is set. I set the location of the SDK in preferences. This doesn’t seem to make any sense. Oh, and every time I restart Unity, it unsets the SDK location and I have to set it again. Has this happened to anyone else?

I also found this exception noted in the console:
assert in file: /Applications/buildAgent/work/14194e8ce88cdf47/Editor/Src/RemoteInput/AndroidRemote.cpp connected to the warning Set-up Android SDK path to make Android remote work

Does anyone have any ideas? Let me know if you need any more information.

I’m still not sure exactly what the problem was, but I solved this by uninstalling Unity 3.5.7 and reinstalling 3.5.6.