dropdown list in edit and read-only mode - asp.net

Question

Hello i have a dropdown list in edit mode and read only mode. If users upload pictures, i want them to chose a category for the uploaded pics and display it in a gridview as below.(See Picture below).
When i include "SelectedValue='<%# Bind("CategoryID")" in edit and item template mode, i get this error "'PictureReadOnlyCategories' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value "
When i removed the "SelectedValue='<%# Bind("CategoryID")" from edit and item template, i get the result on the pic below(screenshot). If u can see the pic below the category is not selected, it just display the -- No Category -- even when i chose a category for the pic.
I want when a pic is uploaded and i category chosen, to display on the gridview. The code for the error message is below:
<EditItemTemplate>
<asp:DropDownList ID="pictureEditCategories" runat="server"
AppendDataBoundItems="True"
DataSourceID="categoriesDataSource"
DataTextField="Name" DataValueField="CategoryID"
SelectedValue='<%# Bind("CategoryID") %>' ValidationGroup="PictureEdit" >
<asp:ListItem Value="" Text="--No Category -- "/>
</asp:DropDownList>
</EditItemTemplate>
<ItemTemplate>
<asp:DropDownList ID="PictureReadOnlyCategories" runat="server"
AppendDataBoundItems="True" DataSourceID="categoriesDataSource"
DataTextField="Name" DataValueField="CategoryID" Enabled="False"
SelectedValue='<%# Bind("CategoryID") %>' ValidationGroup="PictureEdit"
>
<asp:ListItem Value="">-- No Category --</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Title" SortExpression="Title">
<EditItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" EnableViewState="False"
Text='<%# Bind("Title") %>'></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server"
ControlToValidate="TextBox1" Display="Dynamic"
ErrorMessage="must enter a title" ValidationGroup="PictureEdit"></asp:RequiredFieldValidator>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Bind("Title") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Description" SortExpression="Description">
<EditItemTemplate>
<asp:TextBox ID="TextBox2" runat="server" Columns="25" Rows="4"
Text='<%# Bind("Description") %>' TextMode="MultiLine"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server"
ControlToValidate="TextBox2" Display="Dynamic"
ErrorMessage="you must enter a description" ValidationGroup="PictureEdit"></asp:RequiredFieldValidator>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("Description") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Date Added" SortExpression="UploadedOn">
<EditItemTemplate>
<asp:Label ID="Label4" runat="server" Text='<%# Bind("UploadedOn") %>'></asp:Label>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label3" runat="server" Text='<%# Bind("UploadedOn") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:ImageField DataImageUrlField="PictureID"
DataImageUrlFormatString="~/UploadedImages/{0}.jpg" HeaderText="Image"
ReadOnly="True">
<ControlStyle Width="100px" />
</asp:ImageField>
</Columns>
<EditRowStyle BackColor="#2461BF" />
<FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
<RowStyle BackColor="#EFF3FB" />
<SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
<SortedAscendingCellStyle BackColor="#F5F7FB" />
<SortedAscendingHeaderStyle BackColor="#6D95E1" />
<SortedDescendingCellStyle BackColor="#E9EBEF" />
<SortedDescendingHeaderStyle BackColor="#4870BE" />
</asp:GridView>
When i remove the SelectedValue='<%# Bind("CategoryID") %>' from the item and edit template, I get the result for the picture below.
Please i will appreciate your help.
Please you can edit the code or explain it to me since im still learning ASP.net

Answer 1

question answered
You have a DataSource defined with a parameterized query that contains two parameters:
#CategoryID
#UserID
However, you appear to only be populating one of the parameters via the Control Parameters.
Fixing this should be easy enough as you are already pulling the UserID from a query string variable in your other DataSource. You should be able to just copy the QueryStringParameter into your list of SelectParameters for your photo DataSource. Highlighted below:
You could also handle the Selecting event of the datasource and programatically set the UserID in the query that way, but the aforementioned option is easiest. I just want you to be aware of all your options.