Hello @Bahaa_Alaboud,
Have you contacted your Peplink supplier (your local Certified Peplink Partner)?
They should be able to help you with this.
If you are on the latest firmware for your DOME router and SIM Injector, then the next things to be checking is the setup.
I recommend looking through this recent video posted by @PeterWest made for the HD1 DOME LR, as it shows how to configure the router and SIM injector to work together.
( https://youtu.be/rC_HKzRfLNI?si=rO3rvGCD8Rvcgmkt )
If you have any further issues, you can share them here.
Happy to Help,
Marcus 