hello, i'm new with analog design with this pack of ibm and i have a trouble that i can't solve.

I'm doing a simple inverter with Mentor Graphics in this technology and in the schematic i put the subc for the NMOS, but i don't have a contact for the substrate of the PMOS, and when i do the DRC, this is an error message that shows up, i prove to do the contact for myself and this fix the error but i have read that this is not a good design practice. Wha do you say??

And i have another doubt which is the correct interconection of the subc contact with the NMOS transistor??

Thanks.