类型未定义VB.NET

Question

I have a VB.NET project where I create a class that inherits a ComboBox:

Public Class myComboBox
    Inherits System.Windows.Forms.ComboBox
End Class

In the project where I am using this, if I add this control, myComboBox onto a form, I get the following error:

Error 1 Type 'myProject.myComboBox' is not defined.

If I do the exact same thing in a brand new project, everything works just fine. The project has no errors and will execute.

Any ideas?

Answer 1

Your first try would be Clean the solution,and Rebuild it.

Visual Studio > Build > Clean Solution and then Re-Build Solution

Your best bet is to check both your custom-control and project's targeted Dot.Net framework is the same.If they are different,then this is an obvious error

But as you mentioned , it works in a new project right ? So , create a new project,add all the .vb files from your previous project,double click to load the designer(there might be one or two errors but they are easily fixable).Then you have a completely new project,Now add the .dll of the usercontrol/Custom Control you created.

Hope this helps :)