I applied CSS Form Builder to a page. The type of form that I applied was the registration. I edited this form and removed the email address field. I then finished and got the form onto my page. I then test the form out by tabbing through the fields and entering values for all but the passwords. When I attempt to submit the form I see errors about the passwords not matching and a value being required.
I'm including a screen shot of the result that I'm getting. Please give it a try like I have done and let me know exactly what the result is you are getting when do it like this.