Probably temps too cool, 26-28C is better and down to 22-24C at night. Heat mats are contact heaters and when placed on the wall they just heat the glass and not the frog, air temperature or substrate, so ditch that and get a 25-40watt heat lamp, that should get it eating If your fish tank has a lid that won't hold a fixture you can get screen tops on amazon. Aim for about 70% humidity.