stage doesn't display world maps [closed]

edit

hello everyone
I'm trying to run some world maps in stage simulator. Everything works when writing

rosrun roscd stageros willow-erratic.world

while, when using any other world file (already present in default folder or added to it from internet), I get errors like the following one:

    OpenGL Warning: No pincher, please call crStateSetCurrentPointers() in your SPU
 [Loading willow-four-erratics.world][Image "willow-full.pgm"]
err: Model type laser not found in model typetable (/tmp/buildd/ros-fuerte-stage-1.6.6/debian/ros-fuerte-stage/opt/ros/fuerte/stacks/stage/build/stage/libstage/world.cc CreateModel)
err: Unknown model type laser in world file. (/tmp/buildd/ros-fuerte-stage-1.6.6/debian/ros-fuerte-stage/opt/ros/fuerte/stacks/stage/build/stage/libstage/world.cc CreateModel)

Another error I encountered is

ubisum@ubisum:/opt/ros/fuerte/stacks/stage/world$ rosrun stage stageros autolab.world
OpenGL Warning: No pincher, please call crStateSetCurrentPointers() in your SPU
 [Loading autolab.world][Include chatterbox.inc][Include irobot.inc][Include hokuyo.inc][Include map.inc][Image "bitmaps/autolab.png"]
[FATAL] [1360681774.773654192]: number of position models and laser models must be equal in the world file.
[FATAL] [1360681774.777624430]: BREAKPOINT HIT
    file = /tmp/buildd/ros-fuerte-stage-1.6.6/debian/ros-fuerte-stage/opt/ros/fuerte/stacks/stage/src/stageros.cpp
    line=208

Rilevato trace/breakpoint (core dump creato)

Do you know which are the causes of these two errors and how to solve them?

thanks for support