How accurate or appropriate search results are depends mainly on the search query. Therefore, if necessary, improve your search query in the GMX Search.
You have an approximate search result in mind, but you do not get the matching search result or no search result at all. You can eliminate some reasons for this yourself by checking the search query for grammatical correctness or by making it more precise.
When typing the search query, spelling errors can occur.
You have formulated your search query too complicated or too imprecise.
Try to simplify your search query, try other search terms or specify them further.