Missing required parameter

Hello, I need your help in finding the error. When I go to the site I get the error:

Missing required parameter for [Route: single-campaigns_user] [URI: campaigns-user/campaign-single/{lang}/{cam_id}] [Missing parameter: cam_id].

The {cam_id} parameter is clearly specified in my view file. This is my route: Route::get('/campaign-single/{lang}/{cam_id}', [IndexCampaignController::class, 'singleUser'])->name('single-campaigns_user')->middleware(['auth', 'blocked', 'emailnotverify', 'weblang']);

This is my Controller: public function singleUser (string $lang, int $cam_id, Request $request) {

    // $cam_id = $request->cam_id;
    // $lang = $request->lang;
     
    $user = auth()->user()->id; 
     
    $camdata = Campaign::find($cam_id); 
    
    $camItemExist = false; 
    $m = Menu::getMenu(); 
    $a = User::getRole();        

    if ($camdata && $camdata['owner_id'] == $user) {
        
        $camItems = CampaignItem::where('campaign_id', $cam_id)->get();
        if (count ($camItems) > 0) {
            $camItemExist = true; 
        } 

        return view('campaign.single_user', [
            'camdata' => $camdata,
            'camItems' => $camItems,
            'camItemExist' => $camItemExist,  
            'menu' => $m,
            'role' => $a,
        ]); 
    } else {
        return redirect()->route('all-campaigns_user', ['lang' => app()->getLocale(), ])->with('error', __('general.error')); 
    }
}

This is my view file:

                                    @if (!$item['payused'])
                                        <button type="button" class="btn btn-danger" data-bs-toggle="modal" data-bs-target="#removeModal_{{ $item['id'] }}">
                                           {{ __('general.remove_all') }}
                                        </button>
                                    @endif
                                </p>

I would be very grateful for any help or idea.