Error 3 Could not find file 'bin\Release\Microsoft.LightSwitch.Server.Host.exe'.

Question

We have installed Visual Studio 2012 RC , and upgrading an application from Lightswitch 2011 to Lightswitch 2012 , every works fine in debugging mode but when trying to publish we got this error :

" Error 3 Could not find file 'bin\Release\Microsoft.LightSwitch.Server.Host.exe'.  C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets "

But when we create a new whole lightswitch application , we can publish it very well with no errors.

Could anyone help asap.