thank you very much. I appreciate your quick responses. thanks.

I believe that this requires further in-depth investigation.  I've passed the information on this thread to Devleoper Support, who will create a support case for you.  They'll work with you to investigate why the validator isn't functioning when using a WebDateTimeEdit control as the editor of your grid column, as well as to find any resolutions other than not using the editor control.

Nullable property was not set. I changed my code ...

                //UltraWebGrid1.DisplayLayout.Bands[0].Columns[5].EditorControlID = WebDateTimeEdit1.UniqueID;
                //UltraWebGrid1.DisplayLayout.Bands[0].Columns[5].Type = Infragistics.WebUI.UltraWebGrid.ColumnType.Custom;
                //UltraWebGrid1.DisplayLayout.Bands[0].Columns[5].Header.Title = "mm/dd/yyyy";
                //this.WebDateTimeEdit1.Nullable = true;

still not working. so I commented my code for WebDateTimeEdit. now my RequiredFieldValidator is working for BirthDate.

thanks,

Since you have validators working on other columns, it's likely that the validators are all configured correctly.  Perhaps there's other configuration, whether of the grid or the editor, that's affecting this behavior.

Have you set the Nullable property of your WebDateTimeEdit control to true?  This may affect whether or not the grid views the corresponding cell's value as null.

If you have set Nullable to true and this is still occurring, you might also consider temporarily not using the WebDateTimeEdit control as the column's editor to confirm whether or not it makes a difference.  This obviously not a fix; I ask because it may help further research.

one more thing, my grid has FirstName, Gender and Relationship fields which have Required Field Validators and they are working, only BirthDate column has both RequiredFieldValidator and WebDateTimeEdit. the combination doesn't seem to work.  don't understand what Iam missing here..

thanks.