Value from usercontrol

I have this code:
[code]

Protected Sub Komponenter1_ClickUserControl(ByVal sender As Object, ByVal e As System.EventArgs) Handles Komponenter1.ClickUserControl
Dim userC As UserControl = CType(sender, UserControl)
If Not userC Is Nothing Then
Dim userC2 As UserControl = CType(sender, UserControl)
Dim txt1 As String
Dim i As Integer

txt1 = userC.ID

If txt1.Length = 12 Then
i = 1
Else
i = 2
End If

txt1 = CInt(txt1.Substring(11, i))

userC2.ID = "Komponenter" + CStr(txt1)
userC2.Visible = True
end sub
[code]
which works fine. But if I change the code in the two last line to

Code:

---

userC2.ID = "Komponenter" + CStr(txt1+1)
userC2.Visible = True

---

then I receive an error:

Code:

---

Multiple controls with the same ID 'Komponenter2' were found. FindControl requires that controls have unique IDs.
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.Web.HttpException: Multiple controls with the same ID 'Komponenter2' were found. FindControl requires that controls have unique IDs.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 

Stack Trace:

[HttpException (0x80004005): Multiple controls with the same ID 'Komponenter2' were found. FindControl requires that controls have unique IDs.]
  System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection controls) +134
  System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection controls) +203
  System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +164
  System.Web.UI.Control.FindControl(String id) +9
  System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +74
  System.Web.UI.Page.ProcessRequestMain() +1277

 


--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573

---

Why can't I do that?

The code that I write is needed for an app with a lot of order lines where the next order line becomes visible if the current order line is clicked.

Wow...

Well, you declare txt1 as a string, then assign a numeric value to it using CINT(somestring).

When you changed the second to last line, now you're saying CSTR(txt1+1), which is really funky, because txt1 is a string value.

Logically, how do you add the numeric value 1 to a string that represents a number "100". It certainly is not txt1 + 1, I don't care if it worked by accident for you, which is what it did, perhaps because the VB compiler is so forgiving, but as you found out, the underlying .Net framework is not.

Let's first get this code under control:

VB Code:

Dim userC As UserControl = CType(sender, UserControl)
        If Not userC Is Nothing Then
            Dim userC2 As UserControl = CType(sender, UserControl)
            Dim txt1 As String
            Dim i As Integer = 1
            [b]Dim newID As Integer[/b]
 
            txt1 = userC.ID
 
            If Not txt1.Length = 12 Then i =2
 
            [b]newID = Integer.Parse(txt1.Substring(11, i))
            newID += 1
 
            'for the change that you wanted, txt1 + 1 that caused your error
            userC2.ID = String.Concat("Komponenter", newID.ToString)[/b]
            userC2.Visible = True