There are a number of reasons why some points may not automatically reference no matter your choice of search distance. The two main reasons are: 1) there is too much ambiguity between the matches, and 2) the projections of the points do not match across photographs well. For 1) you should consider taking a different set of photographs with different angles or changing the spacing of the points (if you have control over this). For 2) make sure the camera is well calibrated and the orientation of the stations is good. Also note that the preference called "Use accurate lens distortion correction for projections" in the General tab should be turned on if you have a camera with non-zero lens distortion parameters.