Sometimes invitations via email are not sent

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Execute the application
2. Login in LinkedIn
3. Return to application to inform name, email and other informations to invite

What is the expected output? What do you see instead?
Every time I do this, the invite email should be sent. Instead of, sometimes it 
does not happen.

What version of the product are you using? On what operating system?
I'm developing for Android, using Win7 64bits and linkedin-j modified (it can e 
downloaded here: 
http://stackoverflow.com/questions/12188341/cant-post-anything-on-linkedin-using
-linkedin-j) to accept the scopes of permissions to send invitations.

Please provide any additional information below.

My application sends invitations to users. Ok until here. However I noticed 
that sometimes the invitations are not sent to an email that I already sent 
before.
Is there a limit to send an invitation per email or in a period of time?
I'd like to understand this because I didn't find anything about it in the 
Documentation or internet.
Thanks for the help.

Original issue reported on code.google.com by [email protected] on 28 Dec 2012 at 11:51