Unable to upload file on server : failed to open stream: Is a directory

Works on localhost. But when I upload on server it gives error

Here is my error code:

ErrorException in LecturerController.php line 1081:
file_put_contents(/var/www/k2b/data/www/laravel/dev.oasis-portal.my\files\tasks\dev site login.txt.txt): failed to open stream: Is a directory

My code:

    $title = Input::get('title');
    $description = Input::get('description');
    $group_id = Input::get('group_id');
    $date = Input::get('duedate');
    $filename=Input::get('filename');
    $lecturer_id = Input::get('lecturer_id');

    $timestamps = new \DateTime();

    $ext = Input::get('ext');
    $file =$filename.'.'.$ext;
    //$path = str_replace("/laravel","",base_path()).'/files/tasks/'.$file;

     $path = str_replace("\laravel\dev.oasis-portal.my","\dev.oasis-portal.my",base_path()).'\files\tasks\'.$file;

    $data = Request::get('file');

   

    list($type, $data) = explode(';', $data);
    list(, $data)      = explode(',', $data);

    $data = base64_decode($data);

    

    if (!is_dir(str_replace("\laravel\dev.oasis-portal.my","\dev.oasis-portal.my",base_path()).'\files\tasks\')) {

      File::makeDirectory($path,0777,true);
    }

    //Write to File
    $check = file_put_contents($path, $data);

     


    $fileinformation = array('title' => $title, 'description'=> $description, 'duedate'=>$date, 
      'lecturer_id'=>$lecturer_id, 'file' => $file, 'group_id' => $group_id, 'created_at'=>$timestamps, 'updated_at'=>NULL);