Multiple functions for several joins in a query - how to do it?

[eluser]titanite[/eluser]
Hi guys,

I don't get it. Why is it that when the database entry is NULL, I get this error message:

A PHP Error was encountered
Severity: Notice
Message: Trying to get property of non-object
Filename: libraries/Loader.php(673) : eval()'d code
Line Number: 9

I've checked the Loader.php file, it seems that the problem is with short tags?

What's wrong?