Hey Svetlana, there is no theoretical limitation to where a high-pass filter's cut-off frequency can be. If you have not already, I suggest plotting the magnitude response of your filter to verify it has the characteristics you expect. A function like "fvtool" will help you analyze the filter you created (documentation linked to below).
If the magnitude response is what you expect and, after applying it, you are still getting unexpected results, I suggest you read through the "Practical Introduction to Digital Filtering" documentation linked to below. It will describe how to account for issues like delay and transients that affect a filter's impact (remember, a magnitude response only analyzes the filter's steady-state response).
