Hide subpanel..no way to obtain it?

[gbattine]

Hi,
I'm a newbie of SugarCRM.
I installed SugarCRM 4.5 on Windows 2000 Server, Php 5.2 and Apache 2.2.
SugarCRM works correctly and I also customized it in some modules.
My problem is I'm not able to hide a subpanel in a module.
I read lots of posts on this question and all solutions seems not working on my side.
In particular I'm giving my attention on this post:

http://www.sugarcrm.com/forums/showthread.php?t=27893&highlight=hide+subpanel

I'm trying, for example, to hide leads subpanel from Account module .
Following this discussion I added

 <?php 
unset($layout_defs['Accounts']['subpanel_setup']['leads']); 
?>  

to

custom\modules\Accounts\Ext\Layoutdefs\layoutdefs. ext.php.

Clearing cache and refreshing, I've these warnings:

Warning: aSubPanel::require(modules//subpanels/.php) [function.aSubPanel-require]: failed to open stream: No such file or directory in C:\sugar\include\SubPanel\SubPanelDefinitions.php on line 66

Fatal error: aSubPanel::require() [function.require]: Failed opening required 'modules//subpanels/.php' (include_path='.;C:\Programmi\php\pear;C:\php\pear ') in C:\web\application\include\SubPanel\SubPanelDefini tions.php on line 66

I opened this path and line 66 is:

 require($def_path); 
  

where def_path is so defined:

 $def_path = 'modules/'.$this->_instance_properties['module'].'/subpanels/'.$this->_instance_properties['subpanel_name'].'.php'; 
  

Could anyone help me?
I hope in your help, thanks...