Question

I have two drop down lists. I need a selection made in the second one if there is a selection in the first one.

if((ddl1.SelectedIndex > -1 ) != (ddl2.SelectedIndex > -1))
{
    this.lblError.Visible = true;
}

So basically if the there is a selection in the first one but not the second one then error.

Would it be the drop down it’s self??

      <asp:DropDownList ID="ddlRate1" runat="server">
                   <asp:ListItem Value="">(Select)</asp:ListItem>
                   <asp:ListItem>Initial</asp:ListItem>
                   <asp:ListItem>Moderate</asp:ListItem>
                     </asp:DropDownList>

Answer 1

UPDATED from your comments , UPDATED AGAIN..

this is why I originally wrote it with 2 if statements,

if((ddl1.SelectedIndex > 0  ) {   

     //code to read value from ddl1

             if (ddl2.SelectedIndex == 0))
            {
                this.lblError.Visible = true;
                // or maybe a bool 'IsValid'  maybe..
            }
}

Then assuming you have code like this throughout your form , at the end you could do

if ( this.lblError.Visible == true) {  // code to handle invalid form }

OR..

if ((ddl1.SelectedIndex > 0 )  && (ddl2.SelectedIndex == 0)) {
     this.lblError.Visible = true;
}

Try this for trouble shooting – before the if statement

 this.lblError.Visible = true;
 this.lblError.Text = "ddl1 : " + ddl1.SelectedIndex.ToString() + " ddl2 : " + ddl2.SelectedIndex.ToString();