Boolean Function to constrain another function

Hi there,
If possible i would like some help in the following matter:

I have a function with a button that sendīs values from an excel cell in one sheet to another sheet, and i would like to have another function that checks if another 2 cells are empty and then pops up a msgbox giving a warning about the empty cells.
If the 2 cells are empty the warning is given and the button will not send anything.

At the moment i have something like this: (but the boolean seems not to work, something is wrong, because even with values on the cells CD11 and CE12 on sheet3 the button dont send anything).

Private Sub Btn_Send_Arrival_Click()

    Call Check_ARRIVAL_Code

    MsgBox "before boolean is true"

    'If cell have values, button works and send values
     If ARRIVAL = True Then

        MsgBox "after boolean is true"

        'Send Comp.1 Bagagge
        Sheet1.Range("U34").Value = Sheet5.Range("T143").Value

    End If
    
End Sub

'Check when pessing button if the two ceels are empty
Public Sub Check_ARRIVAL_Code()

    Dim ARRIVAL As Boolean

    If Sheet3.Range("CD11").Value = "" And Sheet3.Range("CE12").Value = "" Then
        MsgBox "Please put values in the empty cells"
        ARRIVAL = False
    Else
        ARRIVAL = True
    End If

End Sub

Thanks.
Have a nice holidays everyone.