tier 4 rejected but leave to remain until 2016

Hello,

I have applied for a tier 4 visa and ive graduated from med school when i applied for this. This is because im not a fully qualified doctor during 1st year of working. I will need to apply tier 2 at the start of my second year of working. My tier 4 application was rejected although i was awarded 30 points for my CAS and 10 points for my Funds. The letter stated that i have no right to appeal but i still have leave to remain or enter until August 2016. My previous tier 4 visa expired in october 2014. Im confused as to why i still have leave to remain when my visa application was rejected?
And what is my next step? Am i still allowed to work since my visa is rejected?