Can't export a circut to Verilog - please explain why?

[VyaCHACHsel]

So I've tried to export a circuit for a hobby project I'm doing (make a guess what is the project :-) ) & I don't understand what does this error mean. The circuit works absolutely fine in simulation, all of the components used are exportable to Verilog/VHDL.

Here's the circuit:

The Program Counter thing in the bottom right corner works just like a counter w/ preset, except whenever it receives a clock pulse while Inc2 signal is high, the counter goes up by 2 instead of by 1.

Can you explain why & where in the circuit this error happens & how to fix it?

[VyaCHACHsel]

Already figured it out myself - I've just had to put the drivers' outputs through an OR gate.