ye i can only think of 2 resons why it would do this:
1) try putting it in a new script file (file,new) and try if it works
2) theres another script unsetting the variabless %high %med and %low, probably isnt though
but anyway mine works ;p, if i can ill see if i can sort it out but might not =/
is there anyone else who has got it to work?