vb.net - Project to project reference - type not CLS compliant -

i have problem regarding public declaration in 1 project makes reference class in different project.

the parent project references dependent project without problem. however, i'm getting warning type member 'user' not cls-compliant. it's declared

public user user 

this declaration made in parent project. user class in supporting project can use type on form without fail. now, try pass off on form - in parent project:

private olduser user olduser = frmusermgt.user  

and thing crashes. stepping through code shows olduser nothing.

i built brand new solution , tested exchange without fail. i've searched solution , project settings until i'm blue in face , can't find difference. it's vs2012 vb solution. can post code needed if above description isn't sufficient - appreciated.