Were your ConeColor refill carts stored with the air vent plugs closed?
Did you remove the vent plug before trying to draw ink out of the exit port?
Did you try to draw ink from the exit port of all carts, or just one?
The R3000 carts come with a syringe and long blunt needle for draw ink ink from the bottle + filling carts, but do not come with the small plastic priming tip that comes with the 3800/3880 carts. Without the priming tip, you can't easily draw ink from the exit valve, because it's sealed closed, and the priming tip is specially designed to open the value and allow ink flow. Using the plain syringe tip, I'm not surprised that you couldn't draw ink from the exit valve, and want to point out that too much pressure can damage the cart by ripping the rubber seal, which can cause ink to leak out...
To reinsert carts that have been stored with ink inside, you will want to shake the carts to get ink in suspension, as pigment ink settles while sitting still. With the R3000 carts, as tjn pointed out, the exit chamber should be about 1/2 filled with ink for proper ink flow. I also recommend topping off carts and resetting chips to carts are physically full + chips read full by your printer. Keep in mind, if you experience cartridge errors after reinstalling the refill carts, you may have dead batteries due to age, in which case you will want to replace batteries by following instructions on the link below, or replace the whole chip with new ones. Chip battery replacement info: http://www.inkjetmall.com/wordpress/product-use/r3000-cartridge-batteries/
I hope this helps.
Please keep me posted, and let me know if you have questions or there's anything else I can help you with.