Impossible to run new apps

Hi mates,

The OS X version is 10.9.4 and Xamarin Version 5.7 (build 661). And we have a business license.

We work with PCL projects with android and ios.

If i use the old apps that we have they do not have any problem (xamarin forms 1.25).

But i try to run a new app (xamarin forms 1.32), the sample app, and i always get the same error:
"Error: Unknown MSBuild failure. Please try building the project again (Tests.iOS)"

Any idea please?

Thanks