I created a simple WebPart in Visual Studio 2010 that I was using to test some functionality for a project. When the WebPart was built and deployed, the messages in the Output box in VS all state that it was deployed successfully. In SharePoint Central Administration, under System Settings -> Farm Solutions, it shows that the WebPart was deployed. However, if I created a WebPart page and try to add that WebPart, it doesn't show up in the Custom Category. Also, it doesn't show up in server_name/sites/site_name/_catalogs/wp/Forms/AllItems.aspx.
Please explain to me what is going on why the WebPart only seems to be "partly deployed", and please suggest a way to solve this issue.
Thank you all in advance for your help and advice!