Neocate tastes gross, have you tasted it? The only way I can describe it is it would be like drinking a bottle or raw potato juice
So bearing that in mind it may take her a while to get used to it. Can you express? if so you can mix the neocate with EBM to help her get used to the taste, you can also try mixing it in with her foods so it becomes a familiar taste.
It took us a while to wean Spencer onto it fully, about a week or two, and then he has been fine ever since.
Other things you can do as a temporary measure are to either add a couple of drops of vanilla essence or golden syrup and then slowly wean off that.
For more help you can ring 0800 NEOCATE and talk to the nutricianist, she is really lovely and a huge help