Yap prolog problem

[bayes5]

Hi everybody,

I'm a beginner in prolog, l'm currently using Yap 5.1.1 on ubuntu 12.04. I have a problem with "clause(H+,B)." predicate:

In the knowledge base i have the fact "p(1)" . but when I do a query such as "clause(p(1), BODY)." it return with "PERMISSION ERROR-

clause(user(1),_105,_106): cannot see clauses for p/1", but I'm sure that is correct because I read it on my prolog book.

Can i solve this problem ? Thank you!

P.S. Sorry for my bad english

 

[bayes5]

I have installed SWI-Prolog and it works, i'll use it...but i can't understand because YAP do that.