WebPart adding Error !!

Question

Hello every Body !
Well, i prepared a WebPart whitch inherits from WebPart  System.Web reference.
The type is labeled as "TestWebPart", i used smartwebpart template so the deployment was easy and successfully.
I activated the WebPart too successfully from Site Collection Feature.
But when i added the web Part in the Home Page it occured this error :
Unable to add selected web part(s):
WebPart : A Web Part or Web Form Control on this connot to display or imported.
THe type could not be found or it is not registered as safe
Notice that in the configuration file Web.config the following line is inserted for the safety of the WebPart :
<SafeControl Assembly="TestWebPart, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" Namespace="TestWebPart" TypeName="TestWebPart" Safe="True" />
I tryed with another without WebPart without Web Controls i mean just using write it functioned successfully !
what's up so ?
Thanks !