Hello Shahad! Now, i've a solution for my problem and it looks like a Bug. First, the order of the functions isn't important, but I think it's a very strange problem with the name of my functions. Here my concrete values: rule when then checkHierachyInstance(...) end function void checkHierachyInstance(...) { checkHierachyInstanceRecursive(...); } function void checkHierachyInstanceRecursive(...) { } As far as i have found out, the error occurs ONLY if I append anything to the functionname "checkHierachyInstance", in my case the word "Recursive". It works if I use a completely different name instead of "checkHierachyInstanceRecursive" or exchange a character in "checkHierachyInstanceRecursive". For example i can use "function void myFunc(...)" or "function void checkHierachyInstancRecursive(...)". The only combination of function names i'm not allowed to use is checkHierachyInstance and checkHierachyInstanceXXXXX I've never seen such a curiosity before. Best regards, michael From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Michael Katai Sent: Monday, May 19, 2008 6:00 PM To: 'Rules Users List' Subject: RE: [rules-users] Call a function from a function? Thank you Shahad for your advise, but i doesn't help. I get still the error. regards, michael From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Shahad Ahmed Sent: Monday, May 19, 2008 3:57 PM To: Rules Users List Subject: Re: [rules-users] Call a function from a function? Hi Michael, I had a similar problem, but found that if I declared func2 before func1 (i.e. func2 appears above func1 in a drl file) then you can call func2 in func1. I'm not sure if this is a bug in drools or a limitation of the parser. Regards Shahad On Mon, May 19, 2008 at 1:58 PM, Michael Katai <mk.others(a)gmx.at&gt; wrote: Hello! Is it possible to call a Function in a Function? For example: rule when then func1(data1, data2); end function void func1(MyClass1 data1, MyClass2 data2) { func2(data1, data2); } function void func2(MyClass1 data1, MyClass2 data2) { } When I do so, i get the error message: func1 : Function Compilation error func1 (line:x): The method func2(MyClass1, MyClass2) is undefined for the type Func1 Any suggestions? michael _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users