pin high then low

hello

I am trying to remote fire a camera shutter using an arduino pro mini.
been following this video Arduino Gestures with MPU6050 Accelerometer - 2016-12-22 - YouTube
and accompanying code

The handleLights() function is called on detecting a gesture using an MPU6050 and this is working fine, setting the pin to HIGH. I can't seem to put the delay and digitalWrite(SHUTTER_PIN, LOW); in the right place and the pin stays high with the code hanging up. when I comment out the delay and set to LOW, it works fine again but stays HIGH.

can anyone help?
thanks
Andre

void handleLights(){
    if(glowing){
        DEBUG_PRINTLN("GLOWING!");
        if(glowEnd == -1)
            glowEnd = millis() + glowDuration;

        if(millis() > glowEnd)
            glowing = false;

        // run glow function here

        blinkState = !blinkState;
    }
    if(!glowing){
        // do some variable cleanup
        glowEnd = -1;
        blinkState = false;
    }
    digitalWrite(LED_PIN, blinkState);
    digitalWrite(SHUTTER_PIN, HIGH);
    delay(500);
    digitalWrite(SHUTTER_PIN, LOW);
}

Your code is too rudimentary for any diagnostics. How are the variables declared?