H1b Extension after three years

My H1B visa got approved in October 2012 but I came to USA in May 2013. Now, in Spetember 2015 my three years will be over so my company is going to file for an extension in April 2014. I am currently working directly in company’s payroll and not working for any staffing agency or indirect client. Please let me know if anyone had any extension issue after three years.Do you see any chance of declining extension in my situation?