What vs of Nuke are you using?

Check to make sure that the forum block is actually in your blocks folder, sometimes ftp clients put things where we don't expect them.

Then go into admin/blocks go past the list of current blocks and there is a place to add blocks. Name it, find the block in the drop down list, and save it.

Then go back up to the previously mentioned list and activate the block.

I'm not sure about the content issue. Do you get any errors anywhere on your site?