sharepoint 2010: sandboxed webpart error

I was just tryng to create a simple webpart in visual studio 2010 (for sharepoint 2010) I created an empty sharepoint project, then added a webpart. I wrote a simple code (pasting it from a book with examples) I Build the project, then deploy it (without errors)

Then when i go to the webpage where i want to add my webpart, i get this error when adding it:

"unhandled exception was thrown by the san开发者_运维问答dboxed code wrapper's Execute method in the partial trust app domain: $Resource:core,ImportErrorMessage;"

Any idea about it? If it's needed i'll post the code of the .cs file

Thanks

i don't know why but the second try worked i can't say exactly what went wrong the first time, but i never get the same problem now

I've figured this one out, its something to do with the manifest and features xml files that are generated along with the project.

When you start you should have a namespace like this.

ASMLab4.DisplayWebPartWithProxy.DisplayWebPartWithProxy

But for some reason in those xml files it's added as

ASMLab4.DisplayWebPartWithProxy.DisplayWebPartWithProxy.

With an extra '.' (dot). The fix open something like notepad++ do a search through the project and at first look for

ASMLab4.DisplayWebPartWithProxy.DisplayWebPartWithProxy..

They should be in the manifest/features files. Change to a single dot so should have something like

<type name="ASMLab4.DisplayWebPartWithProxy.DisplayWebPartWithProxy.DisplayWebPartWithProxy, $SharePoint.Project.AssemblyFullName$" />

Next do a search for a single dot. There should be one in the safe list, remove the single dot. Try the deployment again - should be ok.