for some reason the errorprovider is slow to respond? any ideas

Code:
        If Not IsDate(Me.TextBoxDateSentBack.Text) Then
            ErrorProvider1.SetError(Me.TextBoxDateSentBack, "Needs to be a date format.")
            MsgBox("Needs to be a date format.")
            Me.TextBoxDateSentBack.Select()
            Valid = 0
        Else
            ' Clear the error.
            ErrorProvider1.SetError(Me.TextBoxDateSentBack, "")
            Valid = 1
        End If