[MonoDevelop] Target Runtime

[Ben Timby]

I am having trouble getting started. I just installed monodevelop
3.0.6, and created a hello world project. If I build it, I get the
error: "Error: Framework 'Mono / .NET 4.0' not installed.". I am on
Fedora 17, I installed from source.

I look at Project > Options > Build > Options, trying to change the
target runtime, but that option is greyed out, it is set to "Mono /
.NET 4.0 (not installed)".

Going to Edit > Preferences, mono 2.10.5 is listed as default.

Why is runtime 4 the only option for the project? And why won't it compile?