Imagebuilder and extern repository

I'm add the next repository to repositories.conf file
src/gz IceG_repo https://github.com/4IceG/Modem-extras/raw/main/myrepo

and try to make image, but packages can't add:
Collected errors:

  • opkg_install_cmd: Cannot install package luci-app-3ginfo-lite.
  • opkg_install_cmd: Cannot install package luci-app-sms-tool.
    make[2]: *** [Makefile:187: package_install] Error 255
    make[1]: *** [Makefile:142: _call_image] Error 2
    make: *** [Makefile:260: image] Error 2

How to fix that?