Repro:
<telerik:RadSpreadsheet runat="server" ID="RadSpreadsheet1" />
<telerik:RadSpreadsheet runat="server" ID="RadSpreadsheet2" />
protected void Page_Load(object sender, EventArgs e)
{
var workbook = new Workbook();
var sheet1 = workbook.AddSheet();
AddDateRow(sheet1);
sheet1.Columns = new List<Column>() { new Column() { Index = 1, Width = 150 } };
RadSpreadsheet1.Sheets.Add(sheet1);
RadSpreadsheet2.Sheets.Add(sheet1);
RadSpreadsheet1.ColumnsCount = 5;
RadSpreadsheet1.RowsCount = 10;
}
private void AddDateRow(Worksheet sheet1)
{
var row = new Row() { Index = 0 };
Cell firstCell = new Cell() { Index = 0, Value = "Select Date:", Bold = true };
row.AddCell(firstCell);
Cell secondCell = new Cell() { Index = 1, Value = "", Bold = true, Background = "#fef0cd", Format = "mmmm d, yyyy" };
secondCell.Validation = new Validation()
{
AllowNulls = true,
DataType = "date",
ShowButton = true,
ComparerType = "between",
From = "DATEVALUE(\"1/1/2000\")",
To = "DATEVALUE(\"12/31/2020\")",
Type = "reject",
TitleTemplate = "Invalid date selected",
MessageTemplate = "Select a date between year 2000 and 2020."
};
row.AddCell(secondCell);
sheet1.AddRow(row);
}