Can I now apply for tier 2 extension based on new entrant Salary,as you know I am over 26 years.

I Have recently switched my visa from Tier 1 (Post-Study) to Tier 2 (general), but the problem is that my employer had put the ending date on Certificate of Sponsorship the same as what I previously had on my Tier 1 (PSW), that is 1st May 2014. I asked my HR that why did you put the wrong date and t...