PNG nach SDCARD speichern: EISDIR Fehler

if (storageState.equals(Environment.MEDIA_MOUNTED)) {
            //Set filename accordingly
            fileName += ".PNG";
            
            //Get pictures folder
            String exDir = Environment.getExternalStoragePublicDirectory(
                    Environment.DIRECTORY_PICTURES).toString();
            
            //Create a file to the project directory
            File path = new File(exDir + "/" + projectName);
            
            //Make the project directory if necessary
            path.mkdirs();
            
            File file = new File(path, fileName);
            
            try {
                FileOutputStream out = new FileOutputStream(file);
                bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
                out.flush();
                out.close();
            }
            catch (Exception e) {
                msg = Toast.makeText(
                        context,
                        "Error: Unable to write bitmap data. " + e.getMessage(),
                        Toast.LENGTH_LONG);
                msg.show();
                return false;
            }
        }

projectName = "Sprites";
fileName = "Default";

path.mkdirs();

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="ch.subgate.spritestudio"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="10" />
    
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
[...]

//Create a file to the project directory
            File path = new File(exDir + "/" + projectName);
            
            //Make the project directory if necessary
            path.mkdirs();
            
            File file = new File(path, fileName);

            File file = new File(exDir + "/" + projectName, fileName);
            file.mkdirs();

file.getPath(); // = "/mnt/sdcard/Pictures/Sprites/Default.PNG"

if (file.isDirectory()) {
      Log.d("SpriteStudio", "Yep, that sucks!");
}

Environment.getExternalStoragePublic...

Environment.getExternalStorageDirectory();