Exception caught in basicconveyor when speeding up model

Hey,
When i speed up my model i get the following exceptions (but only when the speed is really high)


time: 11504.877091 exception: Exception Caught in BasicConveyor::getitemposition(fsnode* item) object: /theconveyor
time: 11504.877091 exception: Exception Caught in bcgetitemposition(fsnode* conveyor, fsnode* item)
time: 11504.877091 exception: Exception Caught in ObjectFunction051__project_exec_commandlist_bcgeti temposition_node object: MAIN:/project/exec/commandlist/bcgetitemposition/node class: MAIN:/project/exec/commandlist/bcgetitemposition/node


What do they mean? otherwise the model seems to work (although i sometimes do get the impression that operators walk to the stacked totes, but it' might just be a visual thing)

I attached the model

Kr,
Koen