My breadcrumbs are skipping a level
Drupal core breadcrumbs can be flaky at times.

You may be interested in 


Menu Position ( contrib module )
Custom Breadcrumbs ( contrib module )
hook_preprocess_breadcrumb ( theme preprocess function, set $variables['breadcrumb'] )
theme_breadcrumb ( theme function )


Using one or more of those methods, you can control breadcrumb behaviour.