LibGDX File not found

Question

Im trying to load a tiled map in libGDX with

tileMap = new TmxMapLoader().load("maps/level1.tmx");

but somehow it returns a File not found exception:

Caused by: com.badlogic.gdx.utils.GdxRuntimeException: File not found: maps\level1.tmx (Internal)
at com.badlogic.gdx.files.FileHandle.read(FileHandle.java:136)
at com.badlogic.gdx.files.FileHandle.reader(FileHandle.java:164)
at com.badlogic.gdx.utils.XmlReader.parse(XmlReader.java:81)
... 9 more

I already tried to change the path to "/maps/level1.tmx" and other things but nothing works. It returns the file not found exception every time. Can someone see the error?

The path to the .tmx file is:

assets/maps/level1.tmx

the orginal assets folder is in the android project and in every project, the assets folder is linked..