You need a worksheet change event macro - not a standard macro if you want an automatic pop up.
Put the code below in the worksheet that has your drop downs following the steps below:
To install the code:
1. Right-click the worksheet tab you want to apply it to and choose 'View Code'. This will open the VBE window.
2. Copy the code below from your browser window and paste it into the white space in the VBE window.
3. Close the VBE window and Save the workbook. If you are using Excel 2007 or a later version do a SaveAs and save it as a macro-enabled workbook (.xlsm file extension).
4. Make sure you have enabled macros whenever you open the file or the code will not run.
Code:Private Sub Worksheet_Change(ByVal Target As Range) If Not Intersect(Target, Range("H:H")) Is Nothing Then If LCase(Target.Value) = "employee error" Then If Not IsEmpty(Target) And IsEmpty(Target.Offset(0, 3)) Then MsgBox "Please enter a root cause in cell: " & Target.Offset(0, 3).Address(0, 0) Target.Offset(0, 3).Select End If End If End If End Sub