There are extra letters in the Swedish alphabet. The letters å, ä, and ö follow z, in that order. If you are using a Swedish database, you MUST use the correct Swedish spellings. You can not substitute with an a or an o or a", etc. If you do, you won't get any hits.
A Swedish woman named Ingela Martenius has listed these words as the reason why it is important to use the proper Swedish letters. Note that the only difference is the vowel.
kar - tub
kår - corps
kär - dear
kor - cows
kör - choir
There is a very helpful guide telling how to form those letters on the following site.
If you can't create those letters using those directions, then copy/paste these letters.
Save those letters on your computer so you will always have them when you need them.