<asp:GridView ID="GridView4" runat="server" AutoGenerateColumns="False" 
                    BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" 
                    CellPadding="3" DataKeyNames="IdWorker" DataSourceID="SqlDataSource1" 
                    Height="138px" onselectedindexchanged="GridView4_SelectedIndexChanged" 
                    Width="556px" AllowSorting="True">
                    <Columns>
                        <asp:CommandField ShowSelectButton="True" />
                        <asp:BoundField DataField="Name1" HeaderText="Name1" SortExpression="Name1" />
                        <asp:BoundField DataField="Name2" HeaderText="Name2" SortExpression="Name2" />
                        <asp:BoundField DataField="Name3" HeaderText="Name3" SortExpression="Name3" />
                        <asp:BoundField DataField="DatBirt" HeaderText="DatBirt" 
                            SortExpression="DatBirt" />
                        <asp:BoundField DataField="IdWorker" HeaderText="IdWorker" 
                            SortExpression="IdWorker" InsertVisible="False" ReadOnly="True" />
                        <asp:BoundField DataField="DatWork" HeaderText="DatWork" 
                            SortExpression="DatWork" />
                        <asp:BoundField DataField="post" HeaderText="post" SortExpression="post" />
                        <asp:BoundField DataField="IdDep" HeaderText="IdDep" SortExpression="IdDep" />
                    </Columns>
                    <FooterStyle BackColor="White" ForeColor="#000066" />
                    <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
                    <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
                    <RowStyle ForeColor="#000066" />
                    <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
                    <SortedAscendingCellStyle BackColor="#F1F1F1" />
                    <SortedAscendingHeaderStyle BackColor="#007DBB" />
                    <SortedDescendingCellStyle BackColor="#CAC9C9" />
                    <SortedDescendingHeaderStyle BackColor="#00547E" />
                </asp:GridView>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
             ConnectionString="<%$ ConnectionStrings:WEBConnectionString2 %>" 
             SelectCommand="SELECT [Name1], [Name2], [Name3], [DatBirt], [IdWorker], [DatWork], [post], [IdDep] FROM [Worker]">         </asp:SqlDataSource>

<asp:DropDownList 
        ID="DropDownList2" runat="server" Height="20px" Width="261px" 
            DataSourceID="SqlDataSource3" DataTextField="NameLong" 
            DataValueField="IdDep" 
            onselectedindexchanged="DropDownList2_SelectedIndexChanged">
        </asp:DropDownList>
        
<asp:SqlDataSource ID="SqlDataSource3" runat="server" 
            ConnectionString="<%$ ConnectionStrings:WEBConnectionString %>" 
            onselecting="SqlDataSource3_Selecting" 
            SelectCommand="SELECT [idDep], [NameShort], [KodGal], [NameLong] FROM [Department] WHERE ([KodGal] LIKE '1.4.%')AND ([NameLong] NOT LIKE 'Я-%')"> 
     </asp:SqlDataSource>

SqlDataSource1.SelectCommand = "SELECT [Name1], [Name2], [Name3], [DatBirt], [IdWorker], [DatWork], [post], [IdDep] FROM [Worker] WHERE ([IdDep] = Convert.ToString(DropDownList2.Value))";

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
             ConnectionString="<%$ ConnectionStrings:WEBConnectionString2 %>" 
             SelectCommand="SELECT [Name1], [Name2], [Name3], [DatBirt], [IdWorker], [DatWork], [post], [IdDep] FROM [Worker] "
           FilterExpression="IdDep='{0}'">
<FilterParameters>
<asp:ControlParameter Name="IdDep" ControlId="DropDownList2" PropertyName="SelectedValue"/>
</FilterParameters>

        SqlDataSource1.SelectParameters[0].DefaultValue = DropDownList2.Text;
           SqlDataSource1.DataBind();

Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

Source Error: 


Line 151:            //@IdDep = DropDownList2.Text;
Line 152:          //  SqlDataSource1.SelectCommand = "SELECT [Name1], [Name2], [Name3], [DatBirt], [IdWorker], [DatWork], [post], [IdDep] FROM [Worker] WHERE ([IdDep] = Convert.ToString(DropDownList2.Value))";
Line 153:           SqlDataSource1.SelectParameters[7].DefaultValue = DropDownList2.Text;
Line 154:           SqlDataSource1.DataBind();