epos_hardware_node can't find parameters

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Hey, i tryed to get the epos_hardware package ti work. I have the right parameter in the yaml file and if i started the launch file directly with roslaunch mrd.launch it initalized the motors and I can send with the velocity commad the velocity to one motor.

But when i wnat to start it with the epos_hardware_node like it is told at the wiki I get

ae@AErobotNUC:~$ rosrun epos_hardware epos_hardware_node actuator_right
[ INFO] [1475145806.123784737]: Loading EPOS: actuator_right
[ERROR] [1475145806.133245540]: You must specify an actuator name
[ERROR] [1475145806.135072354]: You must specify a serial number
[ERROR] [1475145806.137558224]: You must specify an operation mode
[ INFO] [1475145806.137672590]: 
[ INFO] [1475145806.230669194]: Waiting for robot_description

I think that the problem is that the node doesn't get the parameter and so i tryed to start first the launch and then the node i get his

ae@AErobotNUC:~$ rosrun epos_hardware epos_hardware_node left
[ INFO] [1475146396.731178459]: Loading EPOS: left
[ERROR] [1475146396.739065881]: You must specify an actuator name
[ERROR] [1475146396.741005635]: You must specify a serial number
[ERROR] [1475146396.742883926]: You must specify an operation mode
[ INFO] [1475146396.743017379]: 
[ INFO] [1475146396.854288335]: Initializing Motors
[ERROR] [1475146396.854556155]: Not Initializing: 0x0, initial construction failed
[ERROR] [1475146396.854641495]: Could not configure motor: left
[FATAL] [1475146396.854699196]: Failed to initialize motors

I'm new at ROS and didn't unterstand the problem, thanks for help