Getting error while implementing simple binary search

/** BinarySearchRecursive
     *
     * @param name = to search
     * @param l = left index
     * @param r = right index
     * @param m = middle index
     */
    public int Binary_search( String name, int l , int r )
    {
        int lenForSearch = name.length();

        if( name.compareToIgnoreCase(AddBook.get(l).get_fname().substring(0,lenForSearch)) == 0 )//found contact's index
        {
            return l;
        }
        else if( l == r )return -1;//contact was not found

        int  m = ( (l+r)/2 );

        if( name.compareToIgnoreCase(AddBook.get(m).get_fname().substring(0,lenForSearch)) > 0 )//name < AddBook[m]
        {
             return Binary_search( name, l , m );
        }

        //here you have missed the return statement
        else return Binary_search( name, m , r );//name > AddBook[m]
    }