cell.isNumber error

Hello,

I'm receiving the error 'Object does not support this property or method' on the line of code containing the "cell.isNumber" function:

With ActiveWorkbook.Worksheets("DO Brdgs Pass. Miles")
        Set rngtest = .Range(.Range("A6"), .Range("A" & .Rows.Count).End(xlUp))
    End With
    
    With Worksheets("DO Brdgs Pass. Miles")
    Set totalrng = .Range("B6", Range("P" & Rows.Count).End(xlUp))
    End With
    For Each cell In totalrng
        If Not cell.IsNumber Then
            With cell.Interior
                .Pattern = xlSolid
                .PatternThemeColor = xlThemeColorAccent1
                .Color = 12632256
                .TintAndShade = 0
                .PatternTintAndShade = 0.599993896298105
            End With
        End If
    Next

Do I need to use something else when calling the isNumber query? Or is my syntax resulting in this error?

Thanks,
Chad

Thanks, HaHobe. I always get confused on what IS a 'WorksheetFunction' and what ISN'T.