Array of Ranges to work out average value PROBLEM!

I'm trying to create an array of ranges to use with the average function, I would like each range to be processed and the average value found to be printed. I'm getting error 1004 "unable to get average property of worksheet function"

Private Sub CommandButton3_Click()
    Dim Ranges(1 To 7) As String
    Dim i As Long
    Dim RngAvrg1 As Long
      
Ranges(1) = "C:C"
Ranges(2) = "D:D"
Ranges(3) = "E:E"
Ranges(4) = "F:F"
Ranges(5) = "G:G"
Ranges(6) = "H:H"
Ranges(7) = "I:I"

i = 1

Do Until i = 7

RngAvrg1 = Application.WorksheetFunction.Average(Worksheets("Task_Data").Range(Ranges(i)))
        Sheets("Task_Data").Range("L" & i).Value = RngAvrg1
        
i = i + 1

Loop
 
    
    
End Sub