Hi, In the sample presented by Microsoft for "DataGridView Custom Column" that represents a MaskedTextBoxColumn, it seems it has a problem in setting properties of maskTextBox using visual tools(Editing DataGridview's columns visually), that it stores null values after changing the properties and it does not keep the modifications. Is there any way to correct it or not? http://msdn2.microsoft.com/en-us/library/ms180996.aspx Thanks in advance. Regards Sajjad