[MonoDevelop] Problem running monodevelop 0.18.1

[luca.f at libero.it]

Hi. I installed mono 1.2.6 and monodevelop 0.18.1 on my Ubuntu (Gutsy) but when I try tu run monodevelop, it doesn't start saying that it's not able to find the MonoDevelop.SourceEditor,0.18.0 addin. I got no warnings or errors during the build process. Has anyone got the same error? 
Has anyone tried to do the same?

Thanks,
Luca