Built-in Overflow Problem

Hey guys,

I have a new 125-gallon glass tank with a built-in overflow. The problem
is that, even though the tank is level, the water level stays below the
plastic rim of the tank. Is there anything short of modifying the
built-in overflow that I can do to increase the water level in the tank?

I tried adjusting the level of the water inside the overflow and that
has no effect, and adding more water just raises the water level in the
sump.

Thanks.