Please see the manufacturers instructions here: https://dracomom.ba/en/video-upute/
For troubleshooting your carrier, here's a great article to help: https://www.carryingmatters.co.uk/troubleshooting-your-buckle-carrier/#:~:text=Here%20are%20some%20troubleshooting%20handy,that%20needs%20pre%2Dclipping%20etc.