yet another issue with my bins...

ok, I used to have a glass 30 gallon tank for Nag. it was working out greatt...nice humidity and tems were perfect. so when I got Nagaina I swithed to plastic bins. (the long ones that you can put stuff under the bed, 2 locking handles on either side, and it bends in the middle.)

my UTH's just dont seem to want to put out some real heat?
I ruined one of them, so I bought a new one. I put both uth's on the lids instead of the bottom of the bins, and they were both brand new, and it still doesnt feel warm to the touch.

I dont know what else to try. I have both uth's plugged into a thermostat, and even when I set it on high its barely warm. I have also plugged it directly to an outlet, and it makes no difference.

any advice? its satarting to get cold up here and I really need to get this fixed so they dont freeze at noght, but I'm out of idea.

*sigh*
any and all advice would be greatly appreciated.