Here is a general guideline that you can do to see why you are unable to print out certain colors.
1) Take the system out and soak and wipe up any excess ink within your 'cartridge carriage' and 'printer well' with napkins. Sparingly use 'rubbing alcohol' to wipe down areas to really clean stubborn areas.
2) DO NOT do more than 1-3 head cleanings per 'printer troubleshooting session'. If printheads are clean, there is no need to 'over-clean' them, for it can cause pools of ink to appear, much like in your situation.
3) ENSURE that the air filters are correctly installed into the proper slot on top of the 'ink tank reservoirs'. Not having them installed is the typical cause of a printer not being able to print certain colors.
4) Take the system out and make sure that there is ink in the "Magenta" and "Yellow" cartridge. If there is no ink in there, follow the instructions in this video
5) EMAIL US with your contact number so we can assist you over the phone if you have any questions or concerns PRIOR to doing any of these steps. email@example.com
Hope this helps out!