catkin use msg error: no matching function for call to ros::NodeHandle::subscribe

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Hi, I want to use a msg defined in a rosbuild package in catkin.

I include the .h file of this msg from the rosbuild package directly, and I can create the object successfully. i.e. tld_msgs::BoundingBox newMsg; but when I want to subscribe to a topic that publish this msg I got a compile error

 error: no matching function for call to ‘ros::NodeHandle::subscribe(const char [20], int, int (&)(const BoundingBox&))’

I create the subscriber like this:

ros::Subscriber sub = n.subscribe("/tld_tracked_object", 20, callback);

and the callback function:

int callback(const tld_msgs::BoundingBox &data) { }

Can anyone figure out my mistake?

Thanks

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I copied the msg file into the catkin workspace with the same package name and compiled successfully.

But I got the same error here.

error: no matching function for call to ‘ros::NodeHandle::subscribe(const char [20], int, int (&)(const BoundingBox&))’

I think it should be the problem in my callback function. and I need to modify this:

ros::Subscriber sub = n.subscribe("/tld_tracked_object", 20, callback);

I googled and find I need to modify it like:

ros::Subscriber sub = n.subscribe("/tld_tracked_object", 20, tld_msgs::BoundingBox callback);

but it says error: ‘callback’ is not a member of ‘tld_msgs’

since there is only a msg folder in my tld_msgs folder, I have no idea how to add this in my msg file...