来自后面代码的Databind（）永远不会到达数据库

Question

My FormView wont DataBind. I get no errors, all the elements are found correctly, when I step through the code everything looks like it works as expecting. The select parameter is set and the FormView is DataBound.

But no data is returned and my database logging shows that the procedure that is meant to be DataBound is never touched.

Update Panel

 <asp:updatepanel ID="upnlMixingTankInfo" runat="server">
<ContentTemplate>
 <asp:formview id="fvMixingTankInfo" runat="server" datasourceid="SqlDataSourceMixingTankInfo">
   <ItemTemplate>
         <asp:label runat="server">Vessel Capacity:</asp:label>
         <asp:TextBox ID="vesselCapacity" runat="server" class="form-control" Text='<%# Bind("fldVesselCapacity")%>'></asp:TextBox>
   </ItemTemplate>
  </asp:formview>
</ContentTemplate>

Code Behind:

SourceDropDownList = sender
  upnlMixingTankInfo = CType(SourceDropDownList.Parent.FindControl("upnlMixingTankInfo"), UpdatePanel)
        fvTankInfo = CTYPE(upnlMixingTankInfo.FindControl("fvMixingTankInfo"), FormView)
        If Not IsNothing(SourceDropDownList.SelectedValue) Then
           SqlDataSourceMixingTankInfo.SelectParameters.Add("TankName", DropDownListEquipmentList.SelectedValue)
        End If
        fvTankInfo.Databind()

SQLDATSOURCE:

         <asp:SqlDataSource ID="SqlDataSourceMixingTankInfo" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ZMConnectionString %>"   
    SelectCommand="EXEC stpWebGetMixTankCapacity @TankName" >
    <SelectParameters>
      <asp:Parameter Name="TankName" defaultvalue=""/>
    </SelectParameters>

Answer 1

Few changes in SqlDataSource and done, I've tested using my own sp, modify it according to your usage.

UpdatePanel & FormView

<asp:UpdatePanel ID="upnlMixingTankInfo" runat="server">
    <ContentTemplate>
        <asp:FormView ID="fvMixingTankInfo" runat="server" DataSourceID="SqlDataSource1">
            <ItemTemplate>
                <asp:Label ID="Label1" runat="server">Vessel Capacity:</asp:Label>
                <asp:TextBox ID="vesselCapacity" runat="server" class="form-control" Text='<%# Bind("Name")%>'></asp:TextBox>
            </ItemTemplate>
        </asp:FormView>
    </ContentTemplate>
</asp:UpdatePanel>

Code Behind, I've tested on load, you can use same code wherever you want.

    protected void Page_Load(object sender, EventArgs e)
    {
        SqlDataSource1.SelectParameters.Add("Id", "10");
    }

SqlDataSource with changes:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
    SelectCommand="GetImages" SelectCommandType="StoredProcedure">
</asp:SqlDataSource>

It works perfectly, I've tested before submitting here.