Few words say directly on the problem!

As shown in figure, I want to be a warning prompt, I accomplished using numerical:
The switch ([percent complete]=100, 0,
[percent complete] <100 And [completion time] [percent complete] <100 And 0 & lt; Run time ([] - date ())/480 & lt;=5, 2,
[percent complete] <100 And (/completion time - the date ())/480 & gt; 5, 3)

Can run out of the value 0, but 3 run not to come out, solving the reason,
In addition, also want to please the teacher teach (time difference value/480) why do you write,