c# - VS 2012 Designer could not be shown -

i have usercontrol class employee_employeekeyonerelationuc inherit relationuc inherit relationbase inherit system.window.forms.usercontrol

when try open employee_employeekeyonerelationuc in designer have error :

the designer not shown file because none of classes within can designed. designer inspected following classes in file: employee_employeekeyonerelationuc --- base class 'astusfms.content.relationuc' not loaded. ensure assembly has been referenced , projects have been built.

but when open relationuc , relationbase both showing correctly.

my program still compiling why bothering me ? because have form employeeform use lot of usercontrol (like employee_employeekeyonerelationuc) , when try edit in form, every usercontrol included in form inherit usercontrolebase deleted (left: tfs server, right: local) :

this diff showing designer deleted ucemployee* object. because change combobox's name (combobox has no relation 1 of uc).

i have notice when create new usercontrol file default code showing has error :

but using system.windows.forms; right there. if change usercontrol system.windows.forms.usercontrol works.

i may not clear enough if have question, i'll on answer , test day.

tested on 3 different computer vs2010, vs2012 update 1, vs2012 update 2

when using generics inside form or usercontrol, it's recommended put empty class define generic type. current form derives class.

i put class inside same file. has after actual form code this:

  public partial class employee_employeekeyonerelationuc     : employee_employeekeyonerelation_genericuc   { ... }    public class employee_employeekeyonerelation_genericuc     : relationuc<myobject>   { }