HELP: 加拿大移民被要求考雅思來證明英文能力

I got a question for the Canada green card application. Recently I got a mail from the processing office asking me to take one of the English tests to meet the English proficiency claim in my application. I claimed all high proficiency for reading, writing, listening, and speaking. The letter says the supporting materials that I provided with the application do not support the level that I indicated in the application.

Has anybody ever heard of this? What I provided was a letter that I wrote plus lists of my presentation and papers as well as copies of my previous TOEFL and TSE scores.

Any suggestions on this issue to avoid the test is greatly appreciated.
BTW, I am a PhD student in the US and have been in the US for 5+ years.

Thanks.