It's probably not accepted because this sentence is asking for 'saucepans', not the singular saucepan. It is also a completely different question asking someone where something is and where do they keep something.
Just like they are two different questions in English. You could ask someone, 'Where do you keep your pans?', and then while searching in the area you could follow up with, 'Where are your saucepans?'.
Don't be angry with Duolingo for teaching two different constructions and contexts for sentences when there are also two different variations in English.