Column headers throws errors

[SamT]

Mix and Match

If Target.Count > 1 Then Exit Sub
IF Not Target IsNumeric Then Exit Sub
IF Len(Trim(Target)) <> 4 Then Exit Sub
'That one is tricky if you use 900 for 0900
If (Target > 2400) Or (Target < 1) Then Exit Sub

And how do you deal with 12:59 AM ((Target = 59)

Why not just enter the time as mil-time? IE; 13:30 or 0:59, Both of which Excel recognizes as Mil-time and stores the value as Windows Serial time values?