Can't spawn Portal props, no error message or anything.

I own Portal and GMod, but when I try to spawn something from Portal, I get the noise that it spawned, but no item. I have “Portal” ticked at the main menu, and can use Chell as my player model.
I am kind of a noob at this game, so don’t censor any possibilities becuase you think its too stupid to miss, I very well could have. Thanks in advance.
Running GMod on Windows 7.
EDIT #1) When I re-render a portal prob in the spawnlist, I get that red error sign thing.

Start up Portal. If a window doesn’t popup about converting, verify Portal.

Make sure to put Portal on Steampipe beta. To do that, Open up Steam, go up to the Games tab, and click on View Games Library. Right click on Portal. Click on the Properties option. In the menu that appears, go over to the Betas tab. Change “NO BETA” to “Steampipe Beta”. Then go back to the games page of Portal and click “Play”. Steam will prompt you to convert the content into a newer, more efficient format. Accept, and wait a while for it to finish converting. Once it’s done, you’ll need to click OK to close the dialog box; at some point, Portal will start redownloading via the usual Steam download system.

Portal already been officially moved to SteamPipe, no beta needed.

Okay guys thanks for the great response! Its converting now, I’ll reply again if I have more issues, but hopefully I won’t!

Strange, it isn’t for me.

Try verifying the integrity

It converted, now its downloading stuff, do I need to eait for it to finish downloading before I can use the portal stuff? As it is I still can’t use them.

Yes, wait.