Can someone help me connect this?

Pedal noob. I got a Valeton GP 200, plugged it into power, and plugged my guitar into it and the Valeton into my Fender Mustang LT25 amp. No sound comes out. Adjusted all the master and volume knobs. It does register my guitar as I can tune it on the Valeton. But no sound comes out of the amp. Plugged in headphones into the Valeton as well and no sound. How do I get it to work?