Why am I getting my result as a string of Zs in Quartus?

I am new to Quartus, and have been trying to test out my 32-bit ALU on Quartus 13.1. When I try the functional simulation, I get a string of Zs. The results for the individual components, like the fullAdder, display the results fine. What can I do to view the result(inout) in a hex representation?

Edit: There was an issue with the Quartus 13.1 edition. It works perfectly fine on the 16.1 edition.

• My crystal ball is not supporting schematics/HDL view. – Eugene Sh. Feb 1 '18 at 16:13
• The Zs mean high impedance, so a bit is probably disconnected somewhere. – Samuel Feb 1 '18 at 16:47

module simple(input a,b, output o);

o has the value Z. So you probably want to go over your ALU and make sure that you are actually assigning to your output signal.