Forms generate errors after changing Namespaces of referenced project

[handokowijaya]

In my solution i have 3 projects which contains a business logic, form bases, and front end UI. Originally i use 3 different namespaces for each of them, however i recently changed each namespace to use the same format like for example:
Original Namespace:
Business Logic -> BL
Form bases -> FormBase
UI -> MyProgram.UI

Current Namespace:
Business Logic -> MyProgram.BL
Form bases -> MyProgram.FormBase
UI -> MyProgram.UI

Now there are several problems that occur:
1. Whenever i drop an inheritance form in my UI project with base from FormBase, i got an error and i have to change this line in the form designer file:

Inherits MyProgram.FormBase.FormToInherit
to
Inherits FormBase.FormToInherit


2. All the dataset for the new form that i added since the changes generate errors, and i have to change this line in the form designer file:

MyDataSet = MyProgram.BL.MyDataset
to
MyDataSet = BL.MyDataset

Does anybody knows why it is doing that? And what is the solution for this problem? Thank you for your help!
Han