With new foods it can just be the way you present them how and where.
You say you have not her very long, so she may need time to adjust.
Catalinadee is right in what to do and at what time.
If you mix the pellets with the seed, the chances are she will just pick out the seeds.
I am not a fan of man made pellets and artificial supplements.
But if you are going to feed pellets I would advise you to keep them at around only 25% of the daily diet. You could also do some research about some of the things they are starting to see from long term use of them.
You will not go past a good varied diet of seeds, fruit & veg.
Dark leaf greens, carrots, kumera, (sweet potato), sweetcorn, Kale in moderation.
Here is another idea for you, have you tried to sprout? It is simple, cheap and you know they are fresh and are natural.
I sprout Mung Beans as they are a super food, with lots of natural vitamins and minerals.
Nearly all the birds we tried sprouts on, took to them without much effort.
Even just soaking you seed mix if it fresh will sprout, but you do need to take a bit more care when trying this.
If you do try your hand at sprouting. One way you can be sure they are ok is to feel, taste, smell. If they are slimy or smell throw them away. Do not try to germinate Flax seed as they will become a sticky mess.