Two threads in initializer on rails do not work

Initially, I used one thread to listen on the queue with amazon and worked fine.

aws.rb

Thread.new do
    queue = AWS::SQS::Queue.new(SQSADDR['my_queue'])
    queue.poll do |msg|
    ...

but now I added another thread to listen to another queue:

...    
Thread.new do
    queue = AWS::SQS::Queue.new(SQSADDR['my_another_queue'])
    queue.poll do |msg|
    ...

and now doesn't seem to work. Only the last one gets the answer ...

What's happening?