BACKPAY of a voluntarily resigned employee

I submitted my resignation June 11, 2012 with an effectivity date of June 15, 2012. I went back to my office June 18 to process my clearance however management asked me to stay with the company with a few conditions.

1. It will be a cut & rehire however I don't have to go through the process of waiting for 2 months to be hired again.
2. I would have to go back as a newly hired employee meaning, not regular and no benefits.
3. Salary given will of course be as a newly hired employee.

I took the opportunity and worked for them. After 2 months, I then followed up my back pay since I started working for the company from July 18, 2011 with a lot of VLs and SLs left. Now they informed me I will not get any backpay since I was able to get my salary that June15 pay out.

Now I am actually clueless on what are the rules when it comes to this one?

thanks!

the basic rule is that if you worked, then you are entitled to be paid.