I could resolve the issue. You have to open RadWindows from code behind and refresh data manually.
<
telerik:RadAjaxManager
ID
=
"RadAjaxManager1"
runat
=
"server"
DefaultLoadingPanelID
=
"radloadingprogressbar"
>
<
AjaxSettings
>
<
telerik:AjaxSetting
AjaxControlID
=
"RadGrid1"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"RadGrid1"
LoadingPanelID
=
"radloadingprogressbar"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"rwActivityGrid"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"btnSaveFilter"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"RadGrid1"
UpdatePanelRenderMode
=
"Inline"
></
telerik:AjaxUpdatedControl
>
<
telerik:AjaxUpdatedControl
ControlID
=
"rwActivityGrid"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"btnClearFilter"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"RadGrid1"
UpdatePanelRenderMode
=
"Inline"
></
telerik:AjaxUpdatedControl
>
<
telerik:AjaxUpdatedControl
ControlID
=
"rwActivityGrid"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
</
AjaxSettings
>
</
telerik:RadAjaxManager
>
<
telerik:RadAjaxLoadingPanel
ID
=
"radloadingprogressbar"
runat
=
"server"
Skin
=
"Web20"
>
</
telerik:RadAjaxLoadingPanel
>
<
telerik:RadWindowManager
runat
=
"server"
ID
=
"RadWindowManager1"
>
<
Windows
>
<
telerik:RadWindow
ID
=
"rwActivityGrid"
Modal
=
"true"
Behaviors
=
"Close, Move"
VisibleStatusbar
=
"false"
runat
=
"server"
ReloadOnShow
=
"True"
ShowContentDuringLoad
=
"False"
Width
=
"950px"
Height
=
"500px"
>
<
ContentTemplate
>
<
asp:ImageButton
ID
=
"imbPrint"
ImageUrl
=
"~/_layouts/CAPEXAFEWorkflowDashboardWebPart/printer_4.png"
runat
=
"server"
OnClientClick
=
"PrintContent();return false;"
CssClass
=
"printBtn"
/>
<
div
id
=
"divPrinting"
class
=
"rwDialogPopup radconfirm"
>
AFE / AFD Number:
<
asp:Label
ID
=
"labAFENumber"
runat
=
"server"
Text
=
""
></
asp:Label
>
<
div
>
<
telerik:RadGrid
ID
=
"rgActivityGrid"
runat
=
"server"
AutoGenerateColumns
=
"False"
CellSpacing
=
"0"
GridLines
=
"None"
OnItemDataBound
=
"rgActivityGrid_ItemDataBound"
>
<
MasterTableView
>
<
CommandItemSettings
ExportToPdfText
=
"Export to PDF"
ShowExportToWordButton
=
"true"
ShowExportToExcelButton
=
"true"
ShowExportToCsvButton
=
"true"
></
CommandItemSettings
>
<
RowIndicatorColumn
Visible
=
"True"
FilterControlAltText
=
"Filter RowIndicator column"
>
<
HeaderStyle
Width
=
"20px"
></
HeaderStyle
>
</
RowIndicatorColumn
>
<
ExpandCollapseColumn
Visible
=
"True"
FilterControlAltText
=
"Filter ExpandColumn column"
>
<
HeaderStyle
Width
=
"20px"
></
HeaderStyle
>
</
ExpandCollapseColumn
>
<
NoRecordsTemplate
>
<
div
style
=
"text-align:center;height:40px;padding-top:20px;font-size:small;color:Red"
>
<
span
style
=
"vertical-align: middle;text-align:center"
> No Records To Display</
span
>
</
div
>
</
NoRecordsTemplate
>
<
Columns
>
<
telerik:GridBoundColumn
DataField
=
"ActivityName"
FilterControlAltText
=
"Filter column column"
HeaderText
=
"Activity Name"
UniqueName
=
"ActivityName"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"Destination"
FilterControlAltText
=
"Filter column1 column"
HeaderText
=
"Destination"
UniqueName
=
"Destination"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"StartDate"
FilterControlAltText
=
"Filter column2 column"
HeaderText
=
"Start Date"
UniqueName
=
"StartDate"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"FinishDate"
FilterControlAltText
=
"Filter column3 column"
HeaderText
=
"Finish Date"
UniqueName
=
"FinishDate"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"Status"
FilterControlAltText
=
"Filter column4 column"
HeaderText
=
"Status"
UniqueName
=
"Status"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"Duration"
FilterControlAltText
=
"Filter column5 column"
HeaderText
=
"Duration"
UniqueName
=
"Duration"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
<
telerik:GridBoundColumn
DataField
=
"Final_Action"
FilterControlAltText
=
"Filter column6 column"
HeaderText
=
"Final Action"
UniqueName
=
"Final_Action"
>
<
ItemStyle
Wrap
=
"False"
/>
</
telerik:GridBoundColumn
>
</
Columns
>
<
EditFormSettings
>
<
EditColumn
FilterControlAltText
=
"Filter EditCommandColumn column"
>
</
EditColumn
>
</
EditFormSettings
>
</
MasterTableView
>
<
FilterMenu
EnableImageSprites
=
"False"
>
</
FilterMenu
>
</
telerik:RadGrid
>
</
div
>
</
div
>
</
ContentTemplate
>
</
telerik:RadWindow
>
</
Windows
>
</
telerik:RadWindowManager
>