Exception::=>>Object or Provider is not capable of performing requested operation

Hello, I have problem with Postgre Sql.
I am beginner in Delphi and also in DataBase.
I want to connect to Postgre Sql via Delphi,I use AdoConnection, DataSource, AdoTable and DBGrid.OnCreate application raise error that
"Object or Provider is not capable of Performing requested operation"
and after that If I continue I can see data in DbGrid,but field which type is character isn't shown.
Is there who can help me?
thanks beforehead