Ajax CalendarExtender Not display proper...?

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C#

ASP.NET

CSS

Ajax

I put one Text Box and AjaxCalenderExtender in side my grids EditItemTemplate,
it will like this...

<edititemtemplate>                    
<asp:TextBox ID="TextBoxBELOWROTARYTABLE" runat="server" Text='<%# Bind("BELOWROTARYTABLE", "{0:d-MMM-yyyy HH:mm}") %>'>

<cc1:CalendarExtender ID="MAGDATETextBox_CalendarExtender"  runat="server" Enabled="True"
    TargetControlID="TextBoxBELOWROTARYTABLE" Format="dd-MMM-yyyy">

</edititemtemplate>

it will nice and also popup my calender, but my problem is that the calender will not shown fully but only some part of calender will show....

i think it is because of gridview....

What i need is that when i am in edit mode of my grid data at that time calender will display in full view means it will display properly so what type of css or any property i have to set please help me....