gnu-screen multiuser: Cannot opendir /var/run/screen/S-username: Permission denied

gnu-screen multiuser: Cannot opendir /var/run/screen/S-username:
Permission denied

We have a program running in a screen session, but the user is not always
the same.
I want to automate some things and the command I am trying to use is:
screen -x someuser/sometask -X somecommand
When I am not logged in as 'someuser', I get the error Cannot opendir
/var/run/screen/S-someuser: Permission denied I do not get this error when
I use screen -x or -r - I can in fact access the session and type in
things. When I run the command as root, I get No screen session found.
screen is setuid root, as it is required for multiuser access.
I tried to change the permissions of the directory but then I get the
error Directory /var/run/screen/S-someuser must have mode 700.