The 'DataSource' Property Cannot Be Set Declaratively

This my code for a blog page that shows active blogs:

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Title="Blogs"%><asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

<h3>My blogs</h3>

<asp:GridView ID="Gridview1" runat="server" AllowPaging="true" AutoGenerateColumns="false" DataSource="SqlDataSource1">

<Columns>

<asp:TemplateField>

<HeaderTemplate>

Blog

</HeaderTemplate>

<ItemTemplate>

<b><asp:LinkButton ID="LinkButton1" runat="server" Text='<%#Bind("name") %>'

PostBackUrl='<%#Bind("blogid" "Blog.aspx?Blog={0}" %>' />

 

<br/>

<asp:Label ID="label2" runat="server" Text='<%#Bind ("description") %>' />

 

</ItemTemplate>

<HeaderStyle HorizontalAlign="Left" />

<ItemStyle Width="250px"/>

</asp:TemplateField>

<asp:BoundField DataField="username" HeaderText="Owner">

<HeaderStyle HorizontalAlign="Left" Width="100px" />

<ItemStyle HorizontalAlign="Left" Width="100px" />

</asp:BoundField>

<asp:BoundField DataField="posts" HeaderText="posts">

<HeaderStyle HorizontalAlign="Left" />

<ItemStyle HorizontalAlign="Left" Width="80px" />

</asp:BoundField>

 </Columns>

</asp:GridView><asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ConnectionStrings:BlogConnectionStrings%>"

SelectCommand="SELECT [blogid], [name], [description], [username], [posts] from [Blogs] ORDER By[name]">

</asp:SqlDataSource> </asp:Content>

Compiling that i get the error in the subject specifically for line 4 (in bold). Any ideas?