FrmGrab_IsAlive gets LNK2019 Error- why?

bool EPIPHANCameraControl::RedetectCameras()
{
// // FrmGrab_IsAlive gets LNK2019 Error

return true;

	if (myGrabber == nullptr) {
		return true;  //camera does not exist return true forces a call OpenCamera from somewhere else
	}

	else {

		if (FrmGrab_IsAlive(myGrabber)) {

			return false; // no need for  OpenCamera
		}
		else {

			CloseCamera();

			return true; //  return true forces call OpenCamera from somewhere else
		}

	}

}