Method HasTitle of object chart failed

[SBF12345]

I've been troubleshooting and running this code for a while now with no trouble on the line that is giving an error now. The line below is returning an "method hastitle of object chart failed" error and I'm not sure why? Any ideas what could be causing this?

 .HasTitle = True

within the context of this script:

Dim aa As IntegerDim StartDate As String
Dim EndDate As String
Dim RngStart As Range
Dim RngEnd  As Range
Dim RngStartR As String
Dim RngStartRng As Range
Dim RngEndR As String
Dim RngEndRng As Range
Dim RngXR As String:            RngXR = ActiveWorkbook.Sheets("ActiveSheet").Range("C7").value
Dim RngXR2 As String:           RngXR2 = ActiveWorkbook.Sheets("ActiveSheet").Range("C8").value
Dim sh As Worksheet
Dim chrt As ChartObject
Dim ch As Chart
Dim zz As Integer
Dim NumObs2 As Long


ActiveWorkbook.Sheets("AllDistanceMeasures").Range("I:I,J:J").NumberFormat = "m/d/yy;@"


ActiveWorkbook.Sheets("ActiveSheet").Range("E:E").NumberFormat = "m/d/yy;@"




NumObs2 = Sheets("AllDistanceMeasures").Cells(Rows.Count, 10).End(xlUp).Row


For aa = 5 To NumObs2


    StartDate = Sheets("AllDistanceMeasures").Cells(aa, 9).value
    EndDate = Sheets("AllDistanceMeasures").Cells(aa, 10).value
    
        If StartDate <> "" Then
        
            Set RngStart = Sheets("ActiveSheet").Cells.Find(What:=StartDate, After:=ActiveCell, LookIn:=xlFormulas, _
            LookAt:=xlPart, SearchOrder:=xlByColumns, SearchDirection:=xlNext, _
            MatchCase:=False, SearchFormat:=False).Offset(0, 1)
            
        Else
            MsgBox "StartDate variable for " & Sheets("AllDistanceMeasures").Cells(aa, 9).Address & " not found", vbExclamation
            Exit Sub
            
        End If
        
        RngStartR = RngStart.Address
        
        If EndDate <> "" Then
        
            Set RngEnd = Sheets("ActiveSheet").Cells.Find(What:=EndDate, After:=ActiveCell, LookIn:=xlFormulas, _
            LookAt:=xlPart, SearchOrder:=xlByColumns, SearchDirection:=xlNext, _
            MatchCase:=False, SearchFormat:=False).Offset(0, 1)
            
        Else
            MsgBox "EndDate variable for " & Sheets("AllDistanceMeasures").Cells(aa, 10).Address & " not found", vbExclamation
            Exit Sub
            
        End If
        
        RngEndR = RngEnd.Address
       
    ActiveWorkbook.Sheets("LowDistCharts").Activate
       
    Set sh = Worksheets("LowDistCharts")
    Set chrt = sh.ChartObjects.Add(0, 0, 300, 300)
    Set ch = chrt.Chart
    
    Do While ch.SeriesCollection.Count > 1
    
        ch.SeriesCollection(1).Delete
    
    Loop
    
        With chrt
            .Height = 300
            .Width = 300
            .Top = 1 + ((aa - 4) * 300)
            .Left = 1
        End With
        
        With ch
            .HasTitle = True
            .ChartTitle.Text = aa & " " & StartDate & " to " & EndDate
            .ChartTitle.Font.Size = 8
            .ChartType = xlLine
            .SeriesCollection.NewSeries
            .SeriesCollection(1).Values = ActiveWorkbook.Worksheets("ActiveSheet").Range(RngXR, RngXR2)
            .SeriesCollection.NewSeries
            .SeriesCollection(2).Values = ActiveWorkbook.Worksheets("ActiveSheet").Range(RngStartR, RngEndR)
            .SeriesCollection(2).AxisGroup = 2
            .SeriesCollection(3).Delete
            .HasLegend = False
        End With
        
        For zz = 0 To NumObs - 1
        
            Sheets("ActiveSheet").Range(RngEndR).Offset(zz, 0).Copy
            Sheets("LowDistCharts").Cells(5, aa + 5).Offset(zz, 0).PasteSpecial xlPasteValues
            
        Next zz
    
Next aa

 

[SBF12345]

worth noting...I added the lines

ActiveWorkbook.Sheets("AllDistanceMeasures").Range("I:I,J:J").NumberFormat = "m/d/yy;@"

ActiveWorkbook.Sheets("ActiveSheet").Range("E:E").NumberFormat = "m/d/yy;@"

and the chart title error started showing up. When I remove these lines the code runs fine. How do these lines affect the chart title?