Wambulance

Hello all! My Grey is a pretty female age 2 year + The good news is my family and I do hear her talk. She's able to say "Hello!", "I love you". She also yells my brothers name out loud when I call for him ("David!"). But this is all happening when nobody is looking at her. When people she is familiar with stares at her, she'll chirp and stare back. When I call for her or try to make her repeat the words she's learned to say, she just nods her head furiously in a "yes-up-and-down" motion! Why is this? :confused: