Fixed not a number issue with expression.

Operand.cpp

@@ -23,6 +23,7 @@ namespace jet {
 	 Operand op(in, tag);
 	 string = op.string;
 	 doubleValue = op.doubleValue;
+	 isNumber = op.isNumber;
 	 if(!in.ifNext(")")) 
 	   throw coreutils::Exception("expected ) in expression.");	      
       } else if(in.ifNextIgnoreCase("SUBSTRING")) {