i've solved my problem. the problem is that mocap.srv is not find because i don't have package named 'mocap' (this is my friends project before, using electric ROS. and now i'm re-new it with ROS Indigo. so, i just copying main package of him. mocap is one of package in his workspace). and now i just move the file named *.srv to my srv directory, and change my python code from from mocap.srv import * to from my_package.srv import *