SharePoint not showing in the Categories list

Hi everyone,

thanks in advance for your time and help.

my environment SharePoint 2007 and Visual Studio 2008

when I created a new .Net Project and I go Right click on FEATURES >> Add >> New Item...

I see the following:

But when I Try to modify existing the project and add new feature FEATURES >> Add >> New Item...

I see as follow:

why is this, how can I add new WebPart in the existing project?

thanks again for your time and help.