AVT-8710 does not work with pass-thru ES15
 

Hello. I am having problems with my setup. Currently I have a Panasonic DMR-EZ37V DVD/VCR combo connected to an ordinary DVD recorder. A Panasonic ES15 is connected between them as a pass-thru to correct video and an AVT-8710 is connected after it in the setup. The problem is that with my ES15 connected, my 8710 does not correct issues, such as frame sync; but if not connected, it does correct issues, like my ES15 makes it so my 8710 does not work. Someone on these forums use both and seem to have no problems. Is something wrong with my setup or with one of my units? Thanks in advance.

P.S: I know combos are not recommended for digitizing but I plan on replacing it with an ordinary good '90s VCR sometime in the future. I know S-VHS VCRs are best but I don't want to use one of those. I've tried them and am not entirely satisfied with video playback. I also plan on getting a capture card to replace my DVD recorder in my setup.