How to scale up the Jenkins dynamic slave cluster?

[praveen]

Goal: I would like to use Amazon Ec2 Plugin to add dynamic slaves to Jenkins based on the load.

Architecture: Jenkins Master + 4 slaves + dynamic slaves (based on the requirement)
1st job runs on dynamic slave (no concurrent jobs) - label1 (ami-12345)
2nd job runs concurrently on dynamic slaves - label2 (ami-23314)

These two has different AMI and different labels.

PROBLEM: first job is able to spin up the instance and executes the job everything looks good. If I run the 2nd job Jenkins able to spin up the instance, However if jobs are queued up it's not adding the new slaves.Even though I added the instance to 4 for that AMI.

Can someone please help me on this?

Jenkins v1.656
Amazon EC2 plugin v1.31