Thread: Enabling Custom Channel for targeting - checkbox missing

I am using custom channels and can see the channel data in Performance Reports tab. I am interested in making my custom channels visible to advertisers but unable to find the checkbox to enable channel targeting.
Here is what I see in "My Ads" tab: ((login for URL))
Once I click on one of the Channel names to edit it, I get an Ajax popup box: ((login for URL))

Any insights on how to enable targeting of channels would be appreciated.

It might be because you attached the channel to different sized ad units