Gridview heading coming too large with one row - asp.net

Question

I'm using a gridview in asp.net. The gridview display heading is too large when it has one row.
But if it has pagination, it displays heading normally. I don't have any idea why.
Any help would be appreciated.
<asp:Panel ID="Panel2" runat="server" Height="310px" Width="100%" CssClass="mPanel" BorderStyle ="Groove">
<asp:GridView ID="gridViewResults" runat="server" Width = "100%"
AllowPaging = "true" OnPageIndexChanging="gridViewResults_PageIndexChanging"
CssClass="mGrid" OnSelectedIndexChanged="gridViewResults_SelectedIndexChanged"
Height="300px">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox ID="chkSelect" runat="server" OnCheckedChanged="chkSelect_CheckedChanged" AutoPostBack="true" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</asp:Panel>
this is my code and iam binding it thru databasee..

Answer 1

First try this
<HeaderStyle Width="10%" />
<RowStyle Width="10%" />
If not work than do it from code side for all your colums after binding the gridview
int cou = gdv.Columns.Count;
for (int i = 0; i < cou; i++)
{
gdvProReq.Columns[i].HeaderStyle.Width = 50;
gdvProReq.Columns[i].ItemStyle.Width = 50;
}

Answer 2

The GridView will by default automatically size its columns to fit the largest row... when you paginate, the large row that was stretching out the headers was probably moved to one of the later pages.
You can manually size the columns to avoid the headers from dynamically resizing:
<Columns>
<asp:BoundField DataField="" HeaderText="" ItemStyle-Width="5%" />
<asp:BoundField DataField="" HeaderText="" ItemStyle-Width="25%" />
<asp:BoundField DataField="" HeaderText="" ItemStyle-Width="30%" />
<asp:BoundField DataField="" HeaderText="" ItemStyle-Width="25%" />
<asp:BoundField DataField="" HeaderText="" ItemStyle-Width="10%" />
</Columns>