An error occurred while performing the drop: Object reference not set to an instance of an object

An error occurred while performing the drop: Object reference not set to
an instance of an object

I have a new form that have data source link to Sql Server Database. When
drag and drop the table with the data type=UltaGrid to the form, I get
this error "An error occurred while performing the drop: Object reference
not set to an instance of an object". If I change the data type =
DataGridView, then it's ok.
Would anyone please tell me how to solve this problem? I'd greatly
appreciated your help.