Object reference not set to an instance of an object.

Hi Experts.

I am trying login EPM after my objects (newly created Account user defined Dimension and its respective Model) imported to Quality System.

I have created a new Dimension (User Defined for the the purpose of Account) for the Existing Model in Development System and everything is working fine here in Development System.

I have had already this Model in Quality System, I just imported this new Dimension and the respective Model into Quality System, all the objects are imported and can see through Web. However when i try to login through EPM Connection, I am getting the error "Object reference not set to an instance of an object". I tried refresh the Dimensions and clear the metadata cash but no use. I used to able to connect to this Model before this imports in Quality System. I have also cleared the data of this Model before import.