Excel VBA code only works in debug mode - vba

Question

I've already searched in a bunch of topics and no solution seemed to work for me.
I've an Excel macro file that sometimes works fine, but sometimes only works in stepping mode.
This is a sub inside a main sub that passes a value (message) to a spreadsheet from an Outlook Calendar by category (key). (for this code I adapted from Script to total hours by calendar category in Outlook) .The value goes into the row with the same name as the category and the week value in the column. I've tried the DoEvents and I thought it had worked, but when I tried to run it in a different computer it failed again.
Any ideas?
Option Explicit
Public keyArray
Sub totalCategories()
Dim app As New Outlook.Application
Dim namespace As Outlook.namespace
Dim calendar As Outlook.Folder
Dim appt As Outlook.AppointmentItem
Dim apptList As Outlook.Items
Dim apptListFiltered As Outlook.Items
Dim startDate As String
Dim endDate As String
Dim category As String
Dim duration As Integer
Dim outMsg As String
Dim firstDayOfTheYear As Date
'Going to be used to get start and end date
firstDayOfTheYear = Date
firstDayOfTheYear = "01/01/" & Right(firstDayOfTheYear, 4)
' Access appointment list
Set namespace = app.GetNamespace("MAPI")
Set calendar = namespace.GetDefaultFolder(olFolderCalendar)
Set apptList = calendar.Items
' Include recurring appointments and sort the list
apptList.IncludeRecurrences = True
apptList.Sort "[Start]"
' Get selected date
startDate = firstDayOfTheYear + 7 * (CInt(SelectWeek.week) - 1)
endDate = firstDayOfTheYear + 7 * (CInt(SelectWeek.week) - 1) + 6
startDate = Format(startDate, "dd/MM/yyyy") & " 00:01"
endDate = Format(endDate, "dd/MM/yyyy") & " 11:59 PM"
' Filter the appointment list
Dim strFilter As String
strFilter = "[Start] >= '" & startDate & "'" & " AND [End] <= '" & endDate & "'"
Set apptListFiltered = apptList.Restrict(strFilter)
' Loop through the appointments and total for each category
Dim catHours
Set catHours = CreateObject("Scripting.Dictionary")
For Each appt In apptListFiltered
category = appt.Categories
duration = appt.duration
If catHours.Exists(category) Then
catHours(category) = catHours(category) + duration
Else
catHours.Add category, duration
End If
Next
' Loop through the categories
Dim key
keyArray = catHours.Keys
DoEvents 'prevents a bug from happening --> in some cases the total hours weren't divided by categories
For Each key In keyArray
outMsg = catHours(key) / 60
'Print in Realizado sheet --> activities must be in range (name manager) as "atividades"
writeReport SelectWeek.week, outMsg, key
Next
' Clean up objects
Set app = Nothing
Set namespace = Nothing
Set calendar = Nothing
Set appt = Nothing
Set apptList = Nothing
Set apptListFiltered = Nothing
End Sub
Sub writeReport(week, message As String, key)
Dim ws As Worksheet
Dim i As Integer
Dim Activities, nActivities As Integer
Set ws = Sheets("5")
Activities = Range("activities")
nActivities = UBound(Activities)
DoEvents
For i = 1 To nActivities
DoEvents
If key = Cells(i + 8, 2).Value Then
ws.Cells(i + 8, week + 3).Value = CDbl(message)
Exit For
End If
Next i
End Sub

Answer 1

You need to handle errors explicitly so you know exactly what is going on. Trust me that this will save you HEAPS of time troubleshooting your own code, especially in VBA.
Common practice is something like "try, catch, finally".
Dim position as string
Sub foo()
position = "sub function short description"
On Error GoTo catch
Err.Clear
'do stuff
finally:
On Error Resume Next
'do cleanup stuff
Exit Sub
catch:
Debug.Print Right(ThisWorkbook.FullName, Len(ThisWorkbook.FullName) - 3) & ", _
Position: " & errorPosition & " , Error Code: [ " & Hex(Err.number) & "], _
Description: " & Err.Description & ""
Resume finally
End Sub

Answer 2

Problem solved!
From this:
If key = Cells(i + 8, 2).Value Then
ws.Cells(i + 8, week + 3).Value = CDbl(message)
Exit For
End If
To this:
If key = Activities(i, 1) Then
ws.Cells(i + 8, week + 3).Value = CDbl(message)
Exit For
End If