Another useful calculator:
Mission Operations Cost Model,
http://www1.jsc.nasa.gov/bu2/MOCM.html

According to the calculator, if the investment cost
is $300 million, the annual cost of maintaining and
upgrading ground systems, mission control, tracking,
telemetry, command functions, mission planning, data
reduction and analysis, crew training and related
activities is about 9 million dollars.

Where are your numbers?