Cant get converter to work on Chromacolor?

[50scraze]

I decided to give my 71' chromacolor a little more use and hooked it up to an Apex Digital to analog converter. Only problem....I get nothing with the box hooked up! Funny thing is i get a few channels in perfectly with out the converter.

But in order to get all of my channels (i get free cable) I need that converter box! Im hoping this is some simple stupid mistake. All i can get is the guide screen and the picture is very snowy.

I feel like an idiot..this should be simple! help please!