Terrain Tool Issue

I am operating Sims4 on a Windows laptop, Dell Inspiron. The issue is that when I attempt to use the terrain tool to dig down to make a pond or lake, it does not work. I can hear the sound effects as if it were digging, but nothing happens. 

The tool works if I use the terrain tool to dig in an existing pond or lake to make it bigger or deeper. 

Is there something I should check on the gameplay menu, or is it supposed to be this way?

I would appreciate any tips you can provide.

SherylAnn BV