undefined function user_relationships_types_load()

I get a fatal error report when I want to actived the module

Call to undefined function user_relationships_types_load() in /home/.wycliffe/jeroen_m3/driftauthority.com/drupal-6.0/modules/user_relationships/user_relationship_blocks/user_relationship_blocks.module on line 258

This is the error I get, I'm just a newbie, so got no idea what to do.
Do I need to fill something in between the ()?
Could someone help me please?