Hi @Gokul001 thanks for the answer, but when i tried to use in another project there is no error when i run. The error only appear when i use that project. dtFinal.AsEnumerable().Where(Function(a) String.IsNullOrEmpty(a.Field(Of String)(“Email”).ToString) ).CopyToDatatable(), this is my value in assign activity. What do u think about that, do u know how to resolve this problem?