cannot delete some mesh points

hi.

I'm trying to delete some points from a mesh. There's a mountain in the middle of valley aquifer I'm trying to model. I assume the aquifer has a hole in that area(no porous media, just mezosoic rocks) , that's why I try to delete those points from the mesh and set boundary conditions (recharge). In the user manual for version 6.x this is a really simple operation, but somehow the "delete button" is not active as shown in the pic in this picasa link ( https://picasaweb.google.com/lh/photo/I1twrbMwgkmC0j32wVdcnjcqu0fHZjp4pFwkjBediDo?feat=directlink ). Anyone knows what's going on?

Similar situation to this post (http://www.feflow.info/forum/index.php/topic,306.msg672.html#msg672) , except that delete button is not working.

p.s I used the tutorial data to make sure nothing's wrong.

The tool "delete elements" only becomes active when you have selected elements. Currently, you have selected nodes and therefore the button is greyed out. If you select the two elements inside the indicated nodes you will be able to delete them.

thanks, I just found out that element selection is done after activating a parameter like transmissivity in Data panel.