Selecting topo import for a site

[Kiteman48]

I am trying to import a cad file with 3d contour lines to make a topo surface in Revit.
I was told that you select 'topo surface' - Use import- import instance.
I get to this point and it is impossible to select the imported topography file. I click and there is no way to select.
Is there some strange thing that I am doing wrong?
Do I have to explode it?

[jeffh]

When you import the DWG file you have to make sure it is imported into all views. So you need to uncheck "current view only" in the import dialog. Now try to toposurface command. You will be able to select the imported DWG.

[Kiteman48]

Thank You JeffH.
It worked!