Moved from NJ to NY mid-year and work in NYC - Allocate City Income

I lived in NYC for part of the year, then moved to NJ (while still continuing to work in NYC). I am filling out a NY State part-year resident tax return and need to allocate my income based on the time spent as a resident of NYC. However, TurboTax will not let me change the number in the "wages and tips" field from 0 to the actual number. Please help!