Z-visa documents have any Validation problem or not?

Hi! the Chinese government departments issued me "Chinese Z invitation letter" and "Alien employment Licence" at 6th of June 2013, and i am still out of my country for something important to do. I'll go for applying it in my country at 15th of August. My question is, is there any validation problem in above mentioned documents or not? or do i need to get new documents? . Hope you understand my problem.