If your input voltage is 12V, you should be seeing 4.8V across the 10 ohm resistor and 7.2V across the 15 ohm resistor. Make sure you didn’t mix up the resistors. Check the voltage across each resistor. One voltage should be lower than the other. What voltage reading are you getting on each resistor?
I would suggest using larger resistors like 15k ohm (15,000 ohm) and 10k ohm (10,000 ohm). The larger resistors will reduce the current.
If you have a good picture of how you have this wired may help.