Message box that controls running a macro depending on user choice.

Hello , I am new to creating macros. can someone please let me know where I am going wrong. I have an excel workbook for Timesheets and have setup a macro clears all tick boxes. but would like to give the user the options of yes or no prior to running the macro.

Here is the simple code:

Sub ClearCheckBoxes()

  Dim ChkBox As Object
  Dim Wks As Worksheet
  
  if MsgBox ( prompt = "Warning this will clear Timesheet Data, would you like to Continue?",
        Buttons = vbYesNo + vbQuestion, _
        Title = "Clear TimeSheet Data" )= vbNo then
        Exit Sub
    End If
   
    For Each Wks In Worksheets
      For Each ChkBox In Wks.CheckBoxes
        ChkBox.Value = xlOff
      Next ChkBox
    Next Wks

End Sub

I get syntax error can anyone please help?

Thank you