Trying to make a rig to record onto Sony SL-HF450 Betamax VCR

[KekkyLekky]

I'm into this sort of old tech as a side hobby and am definitely an amateur, and I've been wanting to try out the recording feature of my Sony SL-HF450 Betamax VCR.

I've been trying to make a setup to where I can record my Dish Network (the tuner box for the Dish Network is set to cable channel 73) onto my Sony SL-HF450 Betamax VCR, whose tuner cannot reach channel 73. Here's what I tried to do: Connect the RF Dish Network cable to a VHS VCR that can reach channel 73, connect the VCR to a TV through RF and also connecting the VCR to a Panasonic DMR-ES15 through RCA cable, setting the VCR to VCR mode so that it provides output to the DMR-ES15 while still giving a blurry picture to the TV, connecting the DMR-ES15 to an RF modulator, setting the Betamax VCR and the RF modulator to Channel 3, and connecting the RF modulator to the Betamax VCR through RF.

The problem with this setup is, I cannot seem to get the RF modulator to provide output to the Betamax VCR. Its "on" light does not illuminate, and the level meter on the Betamax VCR is blank (indicating a lack of audio input). I have the RF modulator plugged in. Am I using the RF modulator wrong?

And I cannot simply bypass the RF modulator and connect the DMR-ES15 to the Betamax VCR through RCA cable, because the Betamax VCR can apparently only record audio from RCA input. I tried this and was successfully able to record audio onto a blank Betamax tape (though for some reason, the VCR didn't recognize that the broadcast was stereo, and switching the Beta Hi-Fi switch to "on" made the level meter indicate that the audio input was mono, so I had to use normal audio).