dissolve does not work?

Hi I am using RC 2.71 hash 169c95b
When I want to dissolve a vertex or edge or face I get the message “could not create merged face”?
I have tried using the X key, or the menu>mesh>Delete>Dissolve vertex
Is this a known issue?

Is this a known issue?
The issue is you haven’t shown us what you are trying to dissolve. Their are limitation to the mesh you can make, for example faces cannot have holes in them. If you try and make a face with a hole in it, the dissolve cannot work.

As I have been using the dissolve since so many years, I tried to dissolve an edge within a polygon and vertices in line. always the same error message “could not create merged face”
I tested with a cube that I did sub divide and tried to dissolve one edge, same message
see snapshots


Ok When I use the menu delete from the tool bar, and use dissolve it works, but if I use the X key, I get the error message