BC30311: Value of type 'Control' cannot be converted to 'System.Web.UI.WebControls.CheckBox'

 Hi, can somebody help me on this problem. It works at first, but all of a sudden, it fails, and I can't find out why.



1     Sub btnSave_Click(ByVal sender As Object, ByVal e As EventArgs)
3            If Not CheckRequiredField() Then
4                MessageBox("Please complete the input data!")
5                Exit Sub
6            End If
8            Dim nRow As Integer
9            Dim Ctrl As Control
10           Dim chkDelete As Object
11           Dim LookupID, Name, Desc, Type As String
13           nRow = 0
15           For Each Ctrl In phLookUp.Controls
17               If Ctrl.GetType() Is GetType(CheckBox) Then
19                   '   Checked    = Request.Form("chkDelete" & nRow)
20                   LookupID = Request.Form("txtLookupID" & nRow)
21                   Name = Request.Form("txtName" & nRow)
22                   Desc = Request.Form("txtDesc" & nRow)
23                   Type = Request.Form("txtType" & nRow)
25                   If CType(Ctrl, CheckBox).Checked Then '--> This is the line that causes error
26                       '
27                       'delete
28                       strSQL = "DELETE esd_lookup " & _
29                                "WHERE lookup_id = " & LookupID
31                       objAdapter = New System.Data.OracleClient.OracleCommand(strSQL, objConnection)
33                       objRec = objAdapter.ExecuteReader()
35                       objRec.Close()
37                   Else
39                       If LookupID = "New" Then
40                           'insert
41                           strSQL = "INSERT INTO esd_lookup " & _
42                                    "(lookup_id,lookup_type,lookup_desc,lookup_name)" & _
43                                    " (select lookup_seq.nextval, '" & _
44                                    UCase(Type) & "','" & _
45                                    Desc & "','" & _
46                                    Name & "' from dual) "
48                           objAdapter = New System.Data.OracleClient.OracleCommand(strSQL, objConnection)
50                           objRec = objAdapter.ExecuteReader()
52                           objRec.Close()
54                       Else
55                           'update
56                           strSQL = "UPDATE esd_lookup " & _
57                                    "SET lookup_desc = '" & Desc & "' " & _
58                                    ",lookup_name = '" & Name & "' " & _
59                                     "where lookup_id = '" & LookupID & "'"
61                           objAdapter = New System.Data.OracleClient.OracleCommand(strSQL, objConnection)
63                           objRec = objAdapter.ExecuteReader()
65                           objRec.Close()
67                       End If
69                   End If
71                   nRow += 1
73               End If
75           Next
77           Select Case Type
78               Case "MACHINE"
79                   Type = "Machine"
81               Case Else
83           End Select
87           txtItemCountAdd.text = 0
88           Call Header()
89           Call Item(Type)
91       End Sub


1/24/2008 1:55:00 AM
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Maybe instead of this...

Dim Ctrl As Control
You can try this...
Dim Ctrl As WebControl 


1/24/2008 3:20:59 AM


 It solve the initial problem, but then new problem arise, which stated

"Unable to cast object of type 'System.Web.UI.HTMLControls.HtmlGenericControls' to type 'System.Web.UI.WebControls.WebControl'

It comes from this line

For Each Ctrl In phLookUp.Controls


1/24/2008 3:47:55 AM

Looks like it should work, since WebControl also inherits from Control. Are you using any custom controls in your phLookup placeholder that inherits from checkbox? If so that would probably cause this error.

1/24/2008 3:49:02 AM

Web Server controls and HTML Controls  cannot be mixed. If I were you, I would replace your HTML controls with their Web Server equivalent.  You should only use HTML controls if you need to do heavy client-side Javascript or converting an old ASP application to .NET .


Please do not forget to "Mark as correct answer" if your issue has been resolved. 

1/24/2008 4:03:45 AM

I think it does use web server control Galoopta (by the way, i don't write the code, someone else did). I could be wrong. Glad to show the entire code of the page if you want to. The thing is, it works well before this, even yesterday. But suddenly gives error. I'm clueless right nowConfused  

1/24/2008 6:22:15 AM

I change the codeline...


Dim Ctrl As Control



Dim Ctrl As System.Web.UI.Control

It works. But I don't understand why putting the Imports System.Web.UI.Control or Imports System.Web.UI statement at the top didn't work.

1/24/2008 6:53:14 AM
Glad you got it working but like you said, that should not make a difference unless you are getting your scope mixed up with some other control named "Ctrl"
1/27/2008 7:50:54 PM

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