Range.Validation.Add problem with VBA

manni9999de 

The issue with using Range.Validation.Add in VBA often comes down to the way Excel interprets formulas when they are used in VBA. Specifically, formulas in VBA should always be written using English function names and with absolute references when necessary. Additionally, using the right syntax for specifying the range for validation is crucial.

Here's an attempted version of your VBA code with a fix for adding a custom validation rule using ISNUMBER, the English equivalent of ActualNumber.

Dim formel As String
formel = "=ISNUMBER(A10)"

With Columns("A:A").Validation
    .Delete
    .Add Type:=xlValidateCustom, AlertStyle:=xlValidAlertStop, Operator:=xlEqual, Formula1:=formel
    .IgnoreBlank = True
    .InCellDropdown = False
    .ErrorTitle = "Wert eingeben"
    .InputMessage = ""
    .ErrorMessage = "Der Wert muss eine Zahl sein."
    .ShowInput = False
    .ShowError = True
End With

The VBA code is untested and serves as an example only, please backup your file in advance as a precaution.

My answers are voluntary and without guarantee!

Hope this will help you.

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