Current一样要判断
if Tables("用户资料").Current Not Nothing Then
Dim tx As WinForm.TextBox = e.Form.Controls("tx")
Dim str As String = Tables("用户资料").Current("用户账号")
Dim dr As DataRow = DataTables("用户交费表").Find("用户账号 = '" & str & "'","结束时间 Desc")
If dr IsNot Nothing Then
tx.text = dr("结束时间")
End If
end if