The easiest thing would be to use VLOOKUP to put the comment in the cell adjacent to the validation selection.
But if you really need a message, this may be a start:
<font face=Calibri><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> Worksheet_Change(<SPAN style="color:#00007F">ByVal</SPAN> Target <SPAN style="color:#00007F">As</SPAN> Range)<br> <SPAN style="color:#007F00">' Code goes in the Worksheet specific module</SPAN><br> <SPAN style="color:#00007F">Dim</SPAN> rng <SPAN style="color:#00007F">As</SPAN> Range, c <SPAN style="color:#00007F">As</SPAN> Range<br> <SPAN style="color:#00007F">Dim</SPAN> FirstAddress <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN><br> <br> <SPAN style="color:#007F00">' Set Target Range, i.e. Range("A1, B2, C3"), or Range("A1:B3")</SPAN><br> <SPAN style="color:#00007F">Set</SPAN> rng = Target.Parent.Range("A1")<br> <SPAN style="color:#007F00">' Only look at single cell changes</SPAN><br> <SPAN style="color:#00007F">If</SPAN> Target.Count > 1 <SPAN style="color:#00007F">Then</SPAN> <SPAN style="color:#00007F">Exit</SPAN> <SPAN style="color:#00007F">Sub</SPAN><br> <SPAN style="color:#007F00">' Only look at that range</SPAN><br> <SPAN style="color:#00007F">If</SPAN> Intersect(Target, rng) <SPAN style="color:#00007F">Is</SPAN> <SPAN style="color:#00007F">Nothing</SPAN> <SPAN style="color:#00007F">Then</SPAN> <SPAN style="color:#00007F">Exit</SPAN> <SPAN style="color:#00007F">Sub</SPAN><br> <SPAN style="color:#007F00">' Action if Condition(s) are met (do your thing here...)</SPAN><br> <br> <SPAN style="color:#00007F">With</SPAN> Sheets("Data").Range("A:A")<br> <SPAN style="color:#00007F">Set</SPAN> c = .Find(Target.Value, LookIn:=xlValues)<br> <SPAN style="color:#00007F">If</SPAN> <SPAN style="color:#00007F">Not</SPAN> c <SPAN style="color:#00007F">Is</SPAN> <SPAN style="color:#00007F">Nothing</SPAN> <SPAN style="color:#00007F">Then</SPAN><br> FirstAddress = c.Address<br> <SPAN style="color:#00007F">Do</SPAN><br> MsgBox Target.Value & " has/have a " & c.Offset(, 1), vbOKOnly + vbInformation, "Maximum Weight Information"<br> <SPAN style="color:#00007F">Set</SPAN> c = .FindNext(c)<br> <SPAN style="color:#00007F">Loop</SPAN> <SPAN style="color:#00007F">While</SPAN> <SPAN style="color:#00007F">Not</SPAN> c <SPAN style="color:#00007F">Is</SPAN> <SPAN style="color:#00007F">Nothing</SPAN> And c.Address <> FirstAddress<br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN><br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN><br> <br><SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>
HTH,