BuddyPress.org

Did you test BuddyPress before with just the default theme and no plugins? Did you have it working with the default (bp-default) theme before you switched to your theme?

Either way, the first thing I would do now is disable all plugins except BuddyPress.

Next, I would switch the theme to back to the default (bp-default) within Appearance > Themes in your dashboard.

Once you disable all plugins (except BuddyPress) and switch to the bp-default theme, you should confirm that the theme is working similarly to testbp.org.

Assuming that everything is working and you are not seeing any error messages, switch the theme back to your custom theme before you re-activate any of the other plugins. Check to see if you are still seeing an error message.

If you are, double-check steps 1,2,3 at https://codex.buddypress.org/how-to-guides/wordpress-to-buddypress-theme/. (1) Make sure you’ve put the theme extension pack in your custom theme. (2) Make sure you’ve added the following line to the top of the functions.php file for your custom theme:

include( TEMPLATEPATH . '/bp/bp-functions.php' );

(3) And make sure you’ve added the “Tags” line to your custom theme’s CSS header.

Do you still see the error message? If so, try replacing the code you added to the top of your theme’s functions.php with the code as Andy suggested:

include( STYLESHEETPATH . '/bp/bp-functions.php' );

Check for the error message again.

Once you have BuddyPress functioning using your custom theme without any error messages, then you can try activating plugins one-by-one to ensure you can identify any conflicts.

P.S. You mentioned in #10 above that you had modified the core files by adding the functions line of code to the functions.php file. Just to make sure, the core files are in wp-content/plugins/buddypress/. You should not be modifying any files or folders within the core files. All of the customizations you need to make to adapt your custom theme should be within /wp-content/themes/your-theme/ which I believe for you is /wp-content/themes/wp-clear-basic/. So you are adding the theme extension pack within your theme’s folder at /wp-content/themes/wp-clear-basic/. And you are modifying functions.php and style.css within your custom theme’s folder only.