I performed the save as but still I can not do the group operation. Do you think because the part is modeled in context (has references to the other part in assembly).
Group failures are sometimes due to references that are part of features that are not in the group. For example, external sketches can interfere.
The best method of determining this is to select items, such as the rounds, that will group, group them, and then try to drag other features into the group. I recall this gives more diagnostic information about why it won't group - such as "Can't group X without Y"
