Your origin brush needs to go in the middle of your func_train, not the path_corner. Then you highlight the origin brush, and cntl-click to also highlight the func_train. When both are highlighted, do a tie-to-entity. When the dialog box comes up and says "Do you want to tie everything to the existing func_train?" Click "yes". Now you finally have an origin brush in your func_train. When you compile the map, the func_train will show up wherever it's first path_corner is. Adjust the path_corners and recompile to get the func_train to be where you want it.