Correct answer marked incorrect Chinese Characters

In the First 500 Characters in Mandarin Chinese course it asks you to type what you hear. So I type what I hear, correctly, but it says the answer is incorrect. I have tried it with pinyin and characters. Very frustrating as it keeps listing those characters as ones I have yet to learn, but I do know them! How can I progress like this? I have tried typing in both pinyin and character with and without comma between them - nothing gets me a correct mark, but it is correct.
[image|375x500(upload://2aglDlwpRdyYSaGjDWu74bluoSX.png)