SharpTV-VCR Combo will not record a pre set channel other than 3

I have a Zinwell converter box and a Radio Shack antenna, both are properly hooked up to the ant connection (only 1) in back of tv-vcr unit and the yellow and white connections in frt of unit are connected via a cable with r-y-w to converter box and y-w to frt of tv unit.

At the advance record screen..channel 3 is showing in the selection box, if you insert a different channel it will not record that channel/program.

Are there any converter companies that had the foresight to know that there are hundreds of tv-vcr combos still in use?

I understand the mechanics for a stand alone vcr and I know how to manually record on the combo..but I want to be able to preset and for more than one channel and recording times. Thanx