What OS do you have on your computer?
Do you have the full software installed, if available for your OS? See
http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?cc=us&dlc=en&lc=en&product=421991& , select your OS and then click Next. The Ink Level indicator is part of the HP Toolbox or HP Solution Center (depending on the printer). So without the full-software, the service tab (and ink level information) sn't available.
For the OfficeJet 6210, the driver for the all-in-one is part of the Windows OS for Windows 7. So the ink level information isn't available at the computer.
The other way to get the ink level is to have the printer do a print quality self-test. Put plain white letter, A4 or legal sized paper in the paper tray. Then press Setup (on the printer). Press 2 and 5 (selecting Print Report and Self-Test Report). The ink level may not be given exactly. (Use the quality of the ink blocks to determine if the ink needs to be replaced.)
I hope this helps.
Cindy Wells