spawn_model is not loading the urdf or sdf

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I am trying to convert mit_racecar's xacro files into sdf and use them directly. When I convert and use the command

$rosrun gazebo_ros spawn_model -file racecar.sdf -sdf -x 0 -y 0 -z 0 -model MYCAR

it is simply not proceeding further after showing the message below

SpawnModel script started [INFO] [1521071643.959747, 0.000000]: Loading model XML from file [INFO] [1521071643.960363, 0.000000]: Waiting for service /gazebo/spawn_sdf_model

I am not able to understand what is happening behind as it is not showing any error messages. Any help in understanding and resolving this issue would be highly appreciated.

Thanks