Need to advice on wiring mixer and equalizer using Insert cable.

[cheonmu]

Hello.

I'm trying to connect the mixer and equalizer with an insert cable, and I'm using the equipment below.

Mixer: Springs live 4
EQ: Dod SR231Q 31band 2ch
Cable : TRS - 2 TS cable.

I made a cable for testing, connected the mixer and equalizer, and checked the signal coming in.

But if I adjust any frequency on the equalizer even a little bit, I get a loud beeping sound.

I tried making a new cable, but that didn't solve the problem.

I'd like to get some advice on which parts I should check.

Attached below is a screenshot of the mixer I connected.

Thank you.