Error during linking

hi, I recently have a "error during linking" when I added a new funtion "drivers/buttons.h" in CCS, I added in "include path" . It just show up when I use "buttonspoll()" if I don't use it , the debug session works fine. I don't know what to do, Could you help me, please?

undefined   first referenced
  symbol         in file     
 ---------   ----------------
 ButtonsPoll ./main.obj