Ranking issue.

I am trying to create a workbook which will monitor the trailers off loading at our depot.

Column D Shows the arrival date.
Column E Shows the arrival time.
Column F Will show the queue position. (The off load order 1,2,3,4 etc. This varies as other trailers are off loaded).
Column G Shows the date / time when the trailer completed off load.

In cell F3 I entered the following =IF(G3>1," ",(IF(AND(E3=0,G3=0)," ",RANK(E3,$E$2:$E$50,1))))
The result is 2.
A similar function in F5 gives a result of 3.
I had hoped the results would have been 1 (F3) and 2 (F5).
Cell F2 is blank because G2 contains data. If data was removed this would show 1.

Is it possible to alter the relative queue positions (Column F) using "RANK" or maybe another function?

Any assistance would be greatly appreciated.