PHP SSH2 echo to file for stop session

I want to create a stop.sh file for stopping screen session.

$test = "screen_name";

This is the command:
kill -15 $(screen -ls | grep '[0-9]*.$test' | sed -E 's/s+([0-9]+)..*/1/')

And i want to create this file with php ssh2_exec like this:

ssh2_exec($connection, "echo 'kill -15 $(screen -ls | grep '[0-9]*.$test' | sed -E 's/s+([0-9]+)..*/1/')' > /home/test/stop.sh");

But i got this:

sh: 1: Syntax error: "(" unexpected

I tried:

kill -15 $(screen -ls | grep '[0-9]*.$test' | sed -E 's/s+([0-9]+)..*/1/')

but not working..