About 2 hours after giving my tiels their morning seed and pellets, I give them a stalk of still-dripping baby bok choy and a peeled carrot. An hour later, I collect the uneaten portions and stick them back in the fridge in a baggie for the next morning. They eat a good bit each day
I don't start with a whole stalk. First I pull off the outermost 6-10 leaves to save for later. Same with tat soi, leaves of which are smaller but still nicely firm. I might pull as many as 2 dozen of the outermost leaves ringing the stalk.
Instead of a carrot, somedays, they get a long quarter cut of zucchini, sometimes a few loose leaves of red swiss chard or spinach if it's organic. I always feed my birds organic food except their seed. Hard to find good organic seed. The seed I sprout for them are organic, but those fed dry are not.
Remember that tiels are ground feeders. Spread the leaves and carrots on a paper towel on the cage floor and watch your bird run down to check it out.
Regardless of everything else, keep trying!
Paca