Hi Pierre,

Try:
'================
Sub But_test_click()
Dim rng As Range
Dim RngA As Range, RngB As Range
Dim RngBig As Range
Dim rCell As Range
Dim rw As Range
Dim WB As Workbook
Dim SH As Worksheet
Dim msg As String

Set WB = ActiveWorkbook
Set SH = WB.Sheets("Deelnemers")
Set rng = Columns("A:X")

On Error Resume Next
Set RngA = rng.SpecialCells(xlCellTypeConstants, xlErrors)
Set RngB = rng.SpecialCells(xlCellTypeFormulas, xlErrors)
On Error GoTo 0

If Not RngA Is Nothing Then Set RngBig = RngA

If Not RngB Is Nothing Then
If Not RngBig Is Nothing Then
Set RngBig = Union(RngB, RngBig)
Else
Set RngBig = RngB
End If
End If

If Not RngBig Is Nothing Then
For Each rCell In RngBig.Rows
Set RngBig = Union(RngBig, rCell.EntireRow)
Next rCell
msg = "Errors found in rows:"
For Each rw In RngBig.Rows
msg = msg & vbNewLine & rw.Row
Next rw
msg = msg & vbNewLine & _
"Check your input and press the button again please'"
Else
msg = "No errors found"
End If
MsgBox Prompt:=msg, _
Buttons:=vbInformation, _
Title:="ErrorReport"

End Sub
'<<================


Assuming that you have protected the sheet using the UserInterfaceOnly
parameter, it is not necessary to unprotect / reprotect the sheet.

---
Regards,
Norman


"Pierre via OfficeKB.com" <u13950@uwe wrote in message
news:57a4a88217462@uwe...
Hi Norman,

thanks for the UserInterfaceOnly solution !

In my application the user can fill in only 4 columns (B,C,E,and F)
Only C,E and F can cause possible error (because these are colums where
the
user has to input a date, salary and a parttime%. The rest of the columns
are
calculations based on the user input.

The code you gave now gives the first error that it encounters.
Is there a code that would give msgbox stating all the rows where errors
occurred?
By the way, i adapted the code to the following:
sub but_test click()
Dim rng1 As Range
Dim rng2
Set rng1 = Range("A3:X1000")
On Error Resume Next
Sheets("deelnemers").Unprotect Password:="ekmef1"
Set rng2 = rng1.SpecialCells(xlCellTypeFormulas, xlErrors)
On Error GoTo 0
If Not rng2 Is Nothing Then
'Errors found
MsgBox "your input cause an error in row " & rng2.Row - 2 & _
Chr(13) & Chr(13) & "Check your input and press the button again
please'"
Sheets("deelnemers").Protect Password:="ekmef1"
Exit Sub
End If

Please help me again and thanks,
Pierre