If your cockatiel is only use to eating seeds and budgies seeds at that 
it might take some time to get him/her use to other foods, patience is the key and offereing them daily even if there not eaten eventually s/he will try them and you will be able to see which ones s/he likes best, I offer a small amount of seeds daily and then have pellets in the cage when there done there seeds they move on to the pellets it took some time for some of them to come around but eventually they tried them and found out they liked them, have you tried offering other foods? carrots, corn and parsley are big favourites in my house.
it might take some time to get him/her use to other foods, patience is the key and offereing them daily even if there not eaten eventually s/he will try them and you will be able to see which ones s/he likes best, I offer a small amount of seeds daily and then have pellets in the cage when there done there seeds they move on to the pellets it took some time for some of them to come around but eventually they tried them and found out they liked them, have you tried offering other foods? carrots, corn and parsley are big favourites in my house.
