Tanning question? please help..?

so i just spent an hour tanning outside. 30 minutes on my back and 30 minutes on my front. when i came back inside my house i checked to see the results and i didnt tan :| like i got a tiny bit tan cause i saw some tan lines in my bikini area but i was expecting more. why didnt i get darker?? this was my first time tanning btw and i used dry tanning oil if that makes a difference.