Changes made in the MEP context do not take affect until the MEP configuration is activated, using the enable command. See Activating CFM Configuration for CFM configuration activation details.
This example shows how to enable MEP 1000 on myMA1:
System(rw-config)->cfm md string-name myMD1 System(su-config-cfm-md.1)->ma string-name myMA1 System(su-config-cfm-ma.1)->mep 1000 System(su-config-cfm-mep.1000)->enable System(su-config-cfm-mep.1000)->