SqlDataSource Control And Master Page Problem - Please Help

1. Create a new .aspx page and add this inside the form tag:

    <div>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Button" />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
            SelectCommand="SELECT * FROM [Comments]" InsertCommand="INSERT INTO Comments(CommentAuthor, CommentText) VALUES (@auth, @text)">
            <InsertParameters>
                <asp:FormParameter FormField="TextBox1" Name="auth" />
                <asp:FormParameter FormField="TextBox2" Name="text" />
            </InsertParameters>
        </asp:SqlDataSource>
    
    </div>

2. Add the event handler for the button in code behind:

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.SqlDataSource1.Insert()
    End Sub

3. Run the page, enter some text into the textboxes and hit the button. GREAT! The data was successfully inserted into the database.

Now, let's try the exact same thing, but this time lets create a Master Page first. So:

1. Create a new master page.

2. Create a new .aspx page, check the 'select master page' checkbox and then select the newly created master page.

3. Add the exact same as above in between the asp:Content begin and end tags:

    <div>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Button" />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
            SelectCommand="SELECT * FROM [Comments]" InsertCommand="INSERT INTO Comments(CommentAuthor, CommentText) VALUES (@auth, @text)">
            <InsertParameters>
                <asp:FormParameter FormField="TextBox1" Name="auth" />
                <asp:FormParameter FormField="TextBox2" Name="text" />
            </InsertParameters>
        </asp:SqlDataSource>
    
    </div>

4. Add the event handler for the button in code behind.

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.SqlDataSource1.Insert()
    End Sub

5. Run the page, enter some text into the textboxes and hit the button. WHOOT!? This time it doesn't work and the following error appears:

Cannot insert the value NULL into column 'CommentAuthor', table 'C:DOCUMENTS AND SETTINGSSONYMY DOCUMENTSVISUAL STUDIO 2005WEBSITESCOMMENTSAPP_DATACOMMENTS_DB.MDF.dbo.Comments'; column does not allow nulls. INSERT fails.
The statement has been terminated.
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.Data.SqlClient.SqlException: Cannot insert the value NULL into column 'CommentAuthor', table 'C:DOCUMENTS AND SETTINGSSONYMY DOCUMENTSVISUAL STUDIO 2005WEBSITESCOMMENTSAPP_DATACOMMENTS_DB.MDF.dbo.Comments'; column does not allow nulls. INSERT fails.
The statement has been terminated.

Source Error:


Line 4:  
Line 5:      Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Line 6:          Me.SqlDataSource1.Insert()
Line 7:      End Sub
Line 8:  End Class
 

Source File: C:Documents and SettingsSONYMy DocumentsVisual Studio 2005WebSitesComments2.aspx.vb    Line: 6

So can anyone explain why this only works in the first example?

Many thanks,