如何调整gridview宽度

<tr width="100%">
<td class="label" width="100%">
<asp:Label ID="lblCount" runat="server" Text="共有0条记录" SkinID="LabelCount"></asp:Label>
<asp:GridView ID="grdvView" runat="server" width="100%" SkinID="GridView" DataKeyNames="UserID" AutoGenerateColumns="False" OnSelectedIndexChanged="grdvView_SelectedIndexChanged" >
<Columns>
<asp:CommandField ShowSelectButton="True" >
<ItemStyle ForeColor="Red" Width="30px" />
</asp:CommandField>
<asp:BoundField DataField="UserID" HeaderText="UserID" Visible="False" >
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
<asp:BoundField DataField="UserNo" HeaderText="用户编码">
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
<asp:BoundField DataField="UserName" HeaderText="用户名称" >
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
<asp:BoundField DataField="UserDepart" HeaderText="所属部门">
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
<asp:BoundField DataField="UserRole" HeaderText="所属角色" >
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
<asp:BoundField DataField="UserManage" HeaderText="管养单位">
<HeaderStyle HorizontalAlign="Center" />
</asp:BoundField>
</Columns>
</asp:GridView>
</td>
</tr>

可他宽度就是原始的拖拽时的宽度，怪了。请教下！