Android : Android ExifInterface.saveAttributes() JHEAD﹕ Could not open file for write

I write a App to see and change the Exif Data in pictures. I get all the data with no issues from the picture.

i load them in EditText fields to allow the user to change them. At the end of the View i have a button to save the data back to the image and add the image uri to an history file...

All permissions are set for writing and reading...

when i click on the button it saves the image uri to the textfile, but i get an error on the ExifInterface.saveAttributes(); the error in the log is:

E/JHEAD﹕ Could not open file for write

here is my save Button Method with only setting and saving the Tag_Aperture:

public void saveButton(View view) {
    try {
        exif.setAttribute(ExifInterface.TAG_APERTURE, editFields[0].getText().toString());

        exif.saveAttributes();
        String[] history = readFromFile().split(";");
        for(String elem : history) {
            System.out.println(elem);
        }
        writeToHistoryFile(selectedImageUri.toString());
        Toast toast = Toast.makeText(this, "Exif Data saved succesfully!",
                Toast.LENGTH_LONG);
        toast.show();
        finish();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

I need help fast please, its a Project for school, have to send it to my teacher next week and this is my last error... :( Very much thanks