Try another way. Open the file you wish to edit, select an empty track at the end of your current work. Use File > Import which will then provide an Open File Menu. Select the file with the tracks you wish to include and then press Open. The second file will be appended to the end of the first. You can then edit to remove the tracks which you don't need. Because of a bug in this subprogram you will find that the track names of the first eight tracks will be blanked and will need to be re-entered.