sharepoint error when creating a page

I got this error message 开发者_Python百科when i want to create a page in the SharePoint Central Administration :

The base type 'xxxx' is not allowed for this page. The type is not registered as safe.

The .aspx page references a codebehind class. I checked the namespaces, i added the tag in the web.config, everything is fine, but it still doesn't work !

Can someone please tell me why i got this error message ?

Registering controls as safe via direct web.config is a method that will work, however things get complex when you have a farm. If you have a farm you will have to do this in every web.config for every WFE server you have. The preferred way is doing this via solution package, which is what we do in our environment. See this article which helped us.

Is the entry in the SafeControls correct? Does it reference the exact version number of the assembly? Is the public key token correct?

The one thing that often gets me into toruble is the namespace. Use .NET Reflector and open your assembly - navigate to the control and look at the namespace path for that control in the bottom left of the screen. Sometimes I put the name of the control in SafeControls with the wrong namespace path.