Just remove the CopyToDataTable and the column names should be inside { }
dT=dTCommissionData.DefaultView.ToTable(False,{"TERMINAL","TERMINA_LCIF","TERMINAL_NAME","BRANCH","REGION","Number_of_Transactions","TRAN_AMT","AGENT_COMMISSION","INTERSWITCH_COMMISSION"})
Because, DefaultView.ToTable returns a data table only
The documentation link