what's wrong with the shell ?

[Viktoras Didziulis]

Hi,
 
on mouseUp 
get shell(field "outPut")
put it into field "outPut"
end mouseUp
 
Now I write "dir" into field "outPut" and click a button to test - with no
success... Shell returns empty with any shell command I put into shell(). 
What is wrong here ?
 
Viktoras