Graphical Layout tab does not appear for some layout files into Eclipse

I'm facing a problem when developing layout files for Android with Eclipse ADT Plugin. Some of my files, when opened, does not show the Graphical layout tab, just as below:

The others (actually, the older ones), instead, show it correctly.

Does anyone knows what can be done in this case?

Thanks in advan开发者_JAVA技巧ce!

Have you tried right clicking one of the layout files in the Package Explorer view and clicking

Open With -> Android Layout Editor

If you can see the Graphical Editor tab and still if nothing is showing up, restart eclipse. Worked for me!