Fatal error: Only variables can be passed by reference in nodehierarchy_views.module on line 133

Hi,

Just updated to Node Hierarchy 6.x-1.2 on Drupal 6.10. Also running Views 6.x-2.3.
When I enable the nodehierarchy_views modules I get the white screen of death.
Turning on error messages in index.php results in the following error message being displayed on every page:

"Fatal error: Only variables can be passed by reference in /hsphere/local/home/xxx/xxx.com/sites/all/modules/nodehierarchy/nodehierarchy_views/nodehierarchy_views.module on line 133"

I use node hierarchy views throughout this site, so I really need to get this functionality working again.

Thanks in advance,

Marc