the differences of DataRelation class between 1.1 and 2.0

when u use the follow code on 1.1.it will compile without error. 

        }

 

while it will run error on 2.0 with "Cannot create a DataRelation if Parent or Child Columns are not in a DataSet.".

if u want to run normally,u can use this cod:

 

        }

what's your idea?