Muti select ListBox Very inconsistant when running code based on multiple selections

[jimayers]

Hello everybody. I have written a macro utilizing a Multi select ListBox and it is giving no errors. BUT it only works about a third of the time as intended.
I have a listbox full of class names in one column and in the other column the corresponding class code. Example would be Class 1 - CL1.
The CL1 is what the code uses to perform its task. With the class code (CL1) the macro searches for two things in each row of a worksheet and if not present it hides the row. Those 2 things are a cell having a string inside it and the other is a different cell containing the string "CL1." The following is the code in its entirety and works fine when only one item is checked in the ListBox. What I think is the trouble code is bolded.

 Sub Confirm_CheckList()
Application.ScreenUpdating = False


Dim i, T, j As Integer, msg, lst As String, Check As String
Dim cel As Range
Dim lastrow As Long

lastrow = Cells(Rows.Count, 1).End(xlUp).Row


Worksheets("1").Rows(1 & ":" & lastrow).Hidden = False  'to rereset worksheet, all rows visible


'Generate a list of the selected items
With Sheets("1").ListBox1
    For j = 0 To .ListCount - 1
        If .Selected(j) Then
            msg = msg & .List(j) & vbNewLine
        End If
    Next j
End With
j = 0
     
    If msg = vbNullString Then
         'If nothing was selected, tell user and let them try again
        MsgBox "Nothing was selected!  Please make a selection!"
        Application.ScreenUpdating = True
        Exit Sub
    Else
         'Ask the user if they are happy with their selection(s)
        Check = MsgBox("You selected:" & vbNewLine & msg & vbNewLine & _
        "Are you happy with your selections?", _
        vbYesNo + vbInformation, "Please confirm")
    End If
     
    If Check = vbYes Then
         [B]With Sheets("1")
            For Each cel In .Range("Q1:Q" & lastrow)
                If cel.Offset(0, -12) = "" Then
                    cel.Rows.Hidden = True
                    GoTo a
                End If
              
                For T = 0 To .ListBox1.ListCount - 1
                    If .ListBox1.Selected(T) Then
                    lst = Trim(.ListBox1.List(T, 1))
                        
                        If InStr(cel, lst) > 1 Then cel.Rows.Hidden = False  'checks for previously hidden rows need to be visible
                        If InStr(cel, lst) = 0 Then cel.Rows.Hidden = True   'hides everything except for rows with class code (like CL1)
                            
                    End If
                Next T
a:
            Next cel
        End With

T = 0
        
    Else
        With Sheets("1").ListBox1
        'When user chooses NO on user form and wants to try again, so clear listbox selections 
            For i = 0 To .ListCount - 1
                .Selected(i) = False
            Next i
        End With
    End If[/B]
Application.ScreenUpdating = True
End Sub

I am baffled and frustrated. it looks good and sometimes runs well. I am not sure if how the ListBox loads is part of the problem. Below is the code for it:

 Sub Populating_ListBox_withExtractedDATA_2()
Application.ScreenUpdating = False

Sheets("1").ListBox1.Clear 'clear all existing list box items


Dim r, lastrow As Long
Dim Cname, ccode As String
Dim i As Integer

lastrow = Cells(Rows.Count, 1).End(xlUp).Row


With Sheets("1")
i = 0
    For r = 1 To lastrow
        If Cells(r, 3).Value = Cname Then GoTo a
        If Cells(r, 1) = "COURSE TITLE:" Then
            Cname = Cells(r, 3)
            ccode = Mid(Trim(Cells(r, 3).Offset(4, 14)), 1, 3)
            ColumnCount = 2
            ListBox1.AddItem
            ListBox1.List(i, 0) = Cname
            ListBox1.List(i, 1) = ccode
            i = i + 1
        End If
a:
    Next r
End With
Application.ScreenUpdating = True
End Sub

I would appreciate any help and thanks - Jim A

 

[jimayers]

I fixed it, but 'm sure it could be improved to speed it up. The trouble section largely had to do with re-defining T=0, but I cleaned it up a bit to.

                For T = 0 To .ListBox1.ListCount - 1
                    If .ListBox1.Selected(T) = True Then
                    lst = Trim(.ListBox1.List(T, 1))
                        If InStr(cel, lst) > 0 Then
                            cel.Rows.Hidden = False
                            GoTo a
                        Else
                            cel.Rows.Hidden = True
                        End If
                    End If
                Next T
a:
[COLOR=#0000cd][B]T = 0[/B][/COLOR]
            Next cel
        End With