juju can not reach servers : error

I installed maas server and juju client tools,and i have 2 nodes ready on maas server but when I try to run any deploy command or run juju status the nodes going to located to root and I get these error messages:

Please check your credentials or use 'juju bootstrap' to create a new environment. Error details: no reachable servers.
Error: Unable to connect to environment "maas". Please check your credentials or use 'juju bootstrap' to create a new environment.
Error details: no reachable servers
When I run juju bootstrap again I get this error: environment is already bootstrapped

 my environment file,
 environments: maas:
 type: maas
 maas-server: 'maas-server-ip-address/MAAS';
maas-oauth: 'vzgAAtkW9YftwMRDxb:z9EHbEgsBjMNjbP5r4:9AdTb7gMU39FvPBKHsbPYNT9FAtFGscs'
admin-secret: 'my-root-password'
default-series: 'precise