im getting this error
******* script runtime error *******
undefined is not an array, string, or vector: (file 'common_scripts/utility.gsc', line 463)
 while( !level.flag )
               *
Error: called from:
(file 'maps/byzmodz_buildable_mystery_box.gsc', line 45)
 flag_wait("all_players_connected");
 *
Error: called from:
(file 'maps/byzmodz_buildable_mystery_box.gsc', line 38)
 thread lets_build();
        *
Error: called from:
(file 'maps/nazi_zombie_time.gsc', line 113)
 maps\byzmodz_buildable_mystery_box::main();
 *
Error: started from:
(file 'maps/nazi_zombie_time.gsc', line 10)
main()
*

how to fix it? (KVPs are fine)