array_key_exists ERROR updating to GS 3.2.1

[D.O.]

Updating my site from GS 3.2.0 to GS 3.2.1
at line of my template

PHP Code:

echo date('j/m/y',strtotime(returnPageField('namepage','pubDate'))); 


it shows this message:

PHP Code:

Warning: array_key_exists() [function.array-key-exists]:
The second argument should be either an array or an object in
D:\Inetpub\webs\my_site\admin\inc\caching_functions.php on line 114 


Any help?