Hmm You don't get a json string with the CrossLineDetection?
Content-Type: text/plain
Content-Length:905
Code=CrossLineDetection;action=Stop;index=0;data={
"Class" : "Normal",
"CountInGroup" : 1,
"DetectLine" : [
[ 3843, 5677 ],
[ 6512, 5136 ]
],
"Direction" ...