can someone please tell me why im getting these errors??? Im pretty new to creating games, coding, etc... and for some reason every time I close DM and reopen it my icons wont work on the .dmp map! Here are the errors i get:

tatooine.dmp:1:error: undefined type: /turf/bricks
tatooine.dmp:1:error: unknown type
tatooine.dmp:2:error: undefined type: /turf/sand
tatooine.dmp:2:error: unknown type
tatooine.dmp:3:error: undefined type: /turf/floor
tatooine.dmp:3:error: unknown type
tatooine.dmp:4:error: undefined type: /mob/rat
tatooine.dmp:4:error: undefined type: /turf/floor
tatooine.dmp:4:error: unknown type
tatooine.dmp:4:error: unknown type
tatooine.dmp:5:error: undefined type: /mob/rat
tatooine.dmp:5:error: undefined type: /turf/grass
tatooine.dmp:5:error: unknown type
tatooine.dmp:5:error: unknown type
tatooine.dmp:6:error: undefined type: /turf/grass
tatooine.dmp:6:error: unknown type
tatooine.dmp:7:error: undefined type: /turf/floor
tatooine.dmp:7:error: undefined type: /turf/door
tatooine.dmp:7:error: unknown type
tatooine.dmp:7:error: unknown type
tatooine.dmp:8:error: undefined type: /turf/sand
tatooine.dmp:8:error: undefined type: /turf/door
tatooine.dmp:8:error: unknown type
tatooine.dmp:8:error: unknown type
tatooine.dmp:9:error: undefined type: /mob/rat
tatooine.dmp:9:error: undefined type: /turf/sand
tatooine.dmp:9:error: unknown type
tatooine.dmp:9:error: unknown type
tatooine.dmp:10:error: undefined type: /turf/doorh
tatooine.dmp:10:error: unknown type
tatooine.dmp:11:error: undefined type: /mob/jedi
tatooine.dmp:11:error: undefined type: /turf/sand
tatooine.dmp:11:error: unknown type
tatooine.dmp:11:error: unknown type
tatooine.dmp:12:error: undefined type: /turf/wall
tatooine.dmp:12:error: unknown type
tatooine.dmp:13:error: undefined type: /turf/wallt
tatooine.dmp:14:error: unknown type

any comments would be greatly appreciated, thanks!