AWeber::CreationError on Account with 261 Lists

[mcumer]

Hello,

I use the Aweber API for add customers to aweber lists when they purchase.

I use this line of code
service.account.lists.find_by_id(listname.to_i).subscribers.create(new_subscriber)

And It usually work.
With this account with 261 lists, in most lists ( the last on the lists array ) I get the error:

AWeber::CreationError: Object: <public_api.root.Root object at 0x70e3110>, name: u'lists'

How can I fix this and make it working independently on account number of lists?

Thanks.