Macro not trigger on cell value change

These 3 conditions needs to be fulfilled to trigger the worksheet change event.

If Target.Cells.Count > 1 Then Exit Sub
If Not Intersect(Target, Range("R1:R5001")) Is Nothing Then
If LCase(Target.Value) = "yes" Then

Meaning of the below line - Change should happen in one cell otherwise it will exit the change event

If Target.Cells.Count > 1 Then Exit Sub

Meaning of the below line - Change should happen in the range R1:R5001 otherwise it will exit the change event

If Not Intersect(Target, Range("R1:R5001")) Is Nothing Then

Meaning of the below line - Changing Cell (Single Cell) VALUE should be lower case "yes" otherwise it will exit the change event

If LCase(Target.Value) = "yes" Then