Problema para adicionar linea a archivo txt

[Montes28]

hola amigos, tengo un archivo txt y necesito agregarle adicionarle la siguiente linea (Date,High,Low)

Archivo original:
20141002,0.005676,-9.72,93.9
20141002,0.005696,-11.79,93.77
20141002,0.00568,-12.85,93.65
20141002,0.005664,-13.41,93.61
20141002,0.005656,-13.6,93.55

lo estoy haciendo asi:

Código PHP:

File::put(base_path()."/public/image/Potencial.csv", $xdata);
        $file = fopen(base_path()."/public/image/Potencial.csv",'r+');
        fwrite($file,"Date,High,Low");
        fwrite($file,"\r\n");
        fclose($file);
 

pero esto es lo que obtengo:
Date,High,Low
76,-9.72,93.9
20141002,0.005696,-11.79,93.77
20141002,0.00568,-12.85,93.65
20141002,0.005664,-13.41,93.61
20141002,0.005656,-13.6,93.55


que estoy haciendo mal?