[rules-users] Access of global variables ..

Hi, I am a new drools user. how can I access global variable which is set in one ruletable, in the next ruletable in the same decision table(excel sheet) ? If I am directly using the variable , it is taking null, but i had set its value in previous rule table... Is there any solution?? Kiran Narasareddy Computers make very fast, very accurate mistakes.