Why is my printer (Epson DX7400) not working?

Printer taking paper through ok, printer head moving side to side ok, put new inks in and cleaned heads etc. When I do print head check only the blue square comes out, nothing on pink or yellow or black. When I send sheet through to print just get a few very faint letters dotted hapzardly over page. Its as if ink not getting through but have done all cleaning processes through the maintenance programme.