Tire Pressure Pro not displaying correctly

[Cheri Smith]

I've had this PressurePro a couple months now. The few times I plugged in the display 3 of the sensors will start to display within a minute or two. The last one takes about twice as long, maybe 3- 5 minutes. Also it has stopped displaying at night a couple times when parked. It's not low pressure but the 3 dashes (- - -) that display when it's first plugged in. I'm wondering if that's a sign of a weak battery or just the luck of the draw. BTW it's on one of the front tires & the pressure is OK on that tire.
Funny how you get dependent on a gadget like this when I never had one before.

Cheri Smith