Example 4.7 - double tap doesn't work for call service - comes out blank?

Hi, I have tried too many times now to make the call function work. In example 4.7 I can get the rosservice list working without trouble, seeing the \my_service, but when I try to call it, it returns blank space, as shown here:

user:~$ rosservice call /my_service


What am I doing wrong?

Hey @s151766,

Did you run

source ~/catkin_ws/devel/setup.bash? 

…after creating your service?