Bidirectional Pins and inout

I'm trying to understand how to use bidirectional pins and inout. Simple put I have a verilog code that looks like this

input oe;

input a;

output ab;

inout b;

assign b = (oe) ? a : 1'bz:

assign ab = b

The intended operation is that 'ab' will get what is on the pad 'ab' either 'a' or what is driving 'ab' when tri-stated.

The seconds part is the top level is a schematic (.bdf). I have used a 'BIDIR' pin connected to the 'ab' and get a compiler warning that the pin tristate that pin

What am I missing or NOT see?

Thanks