Temp only get to 23.3C with CHE :( plz help

[seks]

There's an ET 60W CHE in the ET wire light fixture (small). I have the rim of the ET wire light fixture hovering just 0.5" or so above the metal grid of the ET terrarium 18x18x12 top cover. The ET digital thermometer probe is stuck to the glass and sits just above the substrate and it's pretty much below where the CHE is placed. The initial temp was 20.7C or so before the CHE was turned ON. I left the CHE turned ON overnight. 7 hrs later, it only reads 23.3C What steps must I do to get the temp to the recommended temp for a pacman frog????????? I'd have thought 60W is more than enough.