The problem is that I restarted the AndtidWiki application on Android after I copied the TiddlyWiki file in internal storage and now it works.
But the idea is that I have a large SDCard and I would like to store my TW file with external files on SDCard.
I searched for permissions and the Storage permission is enabled. I created the andtidwiki folder on sdcard.
In the permissions it displays that andtidwiki was written for an older version of Android.
In the permission settings it appears that the app can modify or delete the content of SDcard and that it can read the content of the SD card.