Graphical Indicators for Variances (Custom Task Field)

I’ve created a formula which I hoped would show a graphical indicator against the status of each task.

The formula I have used is:

IIf([% Complete]=100,"Task completed",IIf(ProjDateConv([Baseline Finish])="NA","Task not agreed",IIf(([Finish]-[Baseline Finish])<=20 And ([Finish]-[Baseline Finish])>7,"Task >1 week late",IIf(([Finish]-[Baseline Finish])>20,"Task >4 weeks late","Task on schedule"))))

The Graphical fields are:

equals "Task completed" x
equals "Task not agreed" Y
equals "Task on schedule" A
equals "Task >1 week late" B
equals "Task >4 weeks late"C

Obviously I have used symbols from the Image drop down box as opposed to X,Y,A,B & C.

The problem I have is that if a task has a greater varians than 20 days (4 weeks) there is nor graphical representation.

Can anyone advise.

Thanks

Steve