If there one color isn't printing, then most likely there is something obstructing it from flowing. First, you should make sure that all the air filters are installed into the ink tanks (they go into the smaller hole). Then go through these steps to get the color going:
1) Take the cartridges out and locate the little 'spikes' inside the printer carriage that 'poke' into the bottom of the cartridges and draw ink from them.
2) Take a napkin with a little bit of rubbing alcohol in it and 'wipe down' the spikes, focusing on the color that isn't coming out. Try not to get rubbing alcohol into the 'spikes'
3) Reinsert the cartridges back in.
4) Print several images that has a lot of the color that isn't printing out.
5) Do one head cleaning.
6) Repeat step 4, step 5, and step 4 one last time.
7) Let the printer sit for 4-5 hours so the color can fill up on the print head.
Finally print this test page located at this URLhttp://www.psc-consulting.ca/fenske/coloradj.gif
You will be able to print out after this, but if the color is coming out streaky, then step away from the printer for 4-5 hours to allow the printhead to soak up the ink. Then repeat these steps again.
Let us know if how this turns out or if you have any questions in regards to these steps. Hope you have a great day!