This is because before call that is start of purepath should be WebServer I think. You see what is behind it and in such case Appmon sometimes has problems with showing you response time of whole purepath. If there is WebServer before, try to instrument it. Now transactions are starting from AsyncRequest, so for measure point of view, transaction can end because it is not waiting for async requests.
Well there is no webserver before this. How can we solve this part. Also i didn't understand this line
"Now transactions are starting from AsyncRequest, so for measure point of view, transaction can end because it is not waiting for async requests."
Look at your screen, first part of purepath is AsyncRequests. Issue with this is that async requests are handled in separate thread. So in general main transaction can not wait for results and return answer immediately. This is why AuthenticateRequests() which is root of PurePath has such small amount of execution time. Below it there are only AsyncRequests.
The questions is if there are all needed sensor packs enabled for agentgroup we are looking at. You can also look at PurePath Duration column (on purepath list) not for response time but this will tell you overall time of transaction with all AsyncRequests.
One more question, is it appmon agent or classic one? If appmon did you try to switch to classic?
If i want to setup a measure for checking Execution Response time, what will it be..? Is it come under..
API Breakdown----Exec Time or Methods------Exec Time..?
Also its using Appmon Agent, i didn't go with Classic. So is there any issue with Appmon agent