Controlling the gain of the reverb through a Midi controller

Question

I wrote this code to control a web application through a Midi controller. A button on the web interface plays a sample. A reverb (created with .createConvolver() method) is added to the sound of the sample; a slider on the web interface controls the gain of the reverb (gainNode11).

function onMIDIMessage (message) {
    console.log(message.data);

    ......

    // Creating the convolution reverb node 
    var impulseResponseBuffer;
    var getSound = new XMLHttpRequest ();
    getSound.open("get", "circular.wav", true);
    getSound.responseType = "arraybuffer";
    const gainNode11 = audioContext.createGain();

    getSound.onload = function () {
        audioContext.decodeAudioData(getSound.response, function(buffer) {
           impulseResponseBuffer = buffer;
        });
    };
    getSound.send();

    //Routing
    var convolver = audioContext.createConvolver();
    convolver.buffer = impulseResponseBuffer;
    track11.connect(convolver);
    convolver.connect(gainNode11);
    gainNode11.connect(checkbox);
    track11.connect(checkbox);
 
    // Reverb gain Midi control  
    if (message.data[0] === 176 && message.data[1] === 50) {

    if (audioContext.state === 'suspended') {
    audioContext.resume();
    }

    // Conversion of the reverb range value 
    var volumeMidi11 = convertRange(message.data[2],[0,127],[0.000,2.000]); 

    gainNode11.gain.value = volumeMidi11;
    volumeControl11.value = volumeMidi11;

    console.log(gainNode11.gain.value);
    }

    //Triggering of the sample by Midi controller 

    //If the slider/knob is moved
    if (message.data[0] === 176 && message.data[1] === 51 && message.data[2] === 127) {
   
    if (audioContext.state === 'suspended') {
    audioContext.resume();
    }

    audioElement11.currentTime = 0;
    audioElement11.play();
    playButton11.style.background = "#fc61c9";
    audioElement11.loop = 'true';
    playButton11.playing = 'true';
    sub11.innerHTML = "Son déclenché";

    }

    //if the slider/knob is not moved 
    if (message.data[0] === 176 && message.data[1] === 51 && message.data[2] < 127) {
    audioElement11.pause();
    playButton11.style = "bg-warning";   
    playButton11.playing = 'false';
    sub11.innerHTML = "Son arrêté";
    }

The controller Midi knob who triggers the sample works fine, but when I rotate the knob who is supposed to control the gain of the reverb, the slider on the web interface moves but no reverb is added to the sound.

Do you have any suggestions?

Thanks in advance.