Group detail block link 'x' member leads to white screen

LS,

In short: I've

• installed OG (version 6.x-2.1),
• enabled just the og main module (as advised in the README.txt)
• activated the group details block
• created a group (working as expected),
• details block shows: '1 member' NOT as a link (as expected)
• enabled OG views,
• when viewing the group node the detail block shows up again (as expected)
• details block shows: '1 member' as a link (as expected)
• Clicking on the '1 member link' presents me with a white screen. (NOT as expected, expected the members list of the group.

I checked the log files and I noticed the next message:

PHP Fatal error:  Call to undefined function my_module_my_function() in /sites/all/modules/cck/content.module(1694) : eval()'d code on line 1, referer: https://example.com/?q=node/483391

I've several content types with CCK fields. (The group- and group_post type have NO cck fields). Some of the CCK fields contain a function in the allowed values PHP section. For instance function my_module_my_function() is giving back a default array. Up to now this is working fine without any php messages/warnings or what so ever.

After I did the aforementioned installation steps the PHP message shows up in the logs.

I've rearranged the CCK-field in various ways (from hard coding the function into the php section of the cck-field to hard coding the values in the allowed value section if the cck-field). They all solved the issue of the white screen after clicking on the link. So this is not really the issue here, The issue is:

I had a working concept (PHP function in a working module, called by a cck-field) and this concept broke after installing OG views and then just only after clicking on the member link. The function: my_module_my_function() is available for drupal, it can, for instance, be called from the devel - execute php code block.

Is seems calling the 'x member' link is triggering all node types (not only the OG related types) in such a way the cck-fields get called (eval'd) in a stage the my_module_my_function() isn't available (yet)

Question(s):
- Is my concept proof/sound or am I overlooking something?
- Any hints on the direction to look for?
- Any similar experiences?

Of course willing to provide more info/details if needed.
Tnx in advance

Best,
VinceW