Sometimes when searching for an ordernumber, we don't know what is its status. It could be helpful in advanced search for orders to add an option on the 'Order status' dropdown to allow searching on any status.
I had recently come across the other bug :) *** This bug has been marked as a duplicate of bug 14092 ***
Oups... I'm becoming bad at searching existing bugs... Sorry for the duplicate, thanks a lot Katrin !
I had to try different searches too, easier if you have seen the bug before!