ncelab: *E,CUVDNF (verilog.vams): Could not determine discipline for this expression .

The error goes away by changing all type "voltage" I/Os to type "electrical".

Andrew Buckett suggested to use the resolveto keyword in your connectrules:

connect electrical,voltage resolveto electrical; 

This avoids changing the I/Os and will only impact nodes where you are connecting voltage to electrical disciplines.