Selected Value in DropdownList in Gridview does not update

Hi everyone. I've created a DropDownList in a GridView, which works ok, but when I select "two", when the page posts back the first item "one" is selected. Can anyone tell me how to fix this?
I've found a few posts asking this question, but not found a solution. Viewstate is not disabled. Am I  missing a DataBind somewhere?
Thanks!
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<form id="form" runat="server">
<asp:GridView ID="GridViewBrowse" runat="server" DataSourceID="SqlDataSource1" AutoGenerateColumns="False" DataKeyNames="client">
<Columns>
<asp:TemplateField HeaderText="Client" SortExpression="Client">
<HeaderTemplate>
Client
<asp:DropDownList ID="Client" runat="server" DataSourceID="SqlDataSourceClients" DataTextField="client" AutoPostBack=& ...