@Giovanni289, normally, when a guest does a search on AirBnB and does not specify any dates, then all the listings on the map will appear (up to a limit of 300).
As @Emiel1 has mentioned, if your listing is set up for long term stays only (28 days or more minimum nights booking), then your listing does NOT show up at all in search when the guest puts in no dates. To have the listing appear in search, the guest has to search for dates that match your minimum and maximum nights settings. Otherwise, your listing is all but invisible.
I don't know if this is the way AirBnB intended search to work, but it is not good for long-term-only listings, especially since the guests don't know that the long-term listings are being hidden like this.
Maybe if enough hosts complain to AirBnB about this search behavior, they will change/fix it.