ERROR: Cannot load message class for [stereo_msgs/RectifiedImage]. Are your messages built? [closed]

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http://answers.ros.org/question/18707... http://answers.ros.org/question/62430... https://github.com/epsilonorion/rosco... http://answers.ros.org/question/57103...

these answers did not help me.

in my workspace, I have my custom message stereo_msgs/RectifiedImage.msg I want to publish that.

when I do rostopic list, I can see "/mycustomtopic"

but when I do rostopic echo, "ERROR: Cannot load message class for [stereo_msgs/RectifiedImage]. Are your messages built?"

my_msg_pub_ = nh.advertise<stereo_msgs::rectifiedimage>("mycustomtopic", 1);

this is in my main function

and in my callback function (i am subscring to other message type),

my_msg_pub_.publish(myimage);

pls help me out