C# ADDON Wizard

I am learning how to create ADDON with C# ADDON Wizard. I have read the DOCs and e-learning in SAP B1 SDK.

I tried to created a simple ADDON step by step following the eLearning. But when I attached a new form from UDO, once I clicked 'OK', the project would disappear, and I could not find anything under the project. In the eLearning, it seemed I should go to 'Form' step. Can anybody explain the reason and what I should do?