Seems like the transistor is not saturating, you have to see a square wave of 0.6V in the base of the TR (like Steve said) or try with a smaller value resistor, altought i think 4.7K is fine..

If the transistor saturates, the colector current should be (12V-0.2V)/10K = 1.18mA (0.2V aprox is VCE sat)
and the colector voltage should be 12V-Ic*Rc
Look the colector with a scope looking for a square signal of nearly 12V and 0.2V

In this case your base current should be (5V-0.6V)/R if R = 5K, so Ib = 0.88mA wich should be enough to make the transistor saturate (if is a small signal one).

Like steve said, make sure the MCU can handle 1mA output source, if not, try with a Darlington approach.

Hope this helps you a bit.
Regards Robert.