One of the board of director sold his unit and does not attent to the board meeting.I just want to know what should we do about it.He does not answer/reply our phone calls.

Unless your by-laws state that a Director must be an owner then the selling of the unit only looks bad politically not legally.

Ensure everyone knows that this board member has sold their unit and therefore no longer has an interest in the corporation.

If the director is not coming to board meetings then a warning should be given to the director that resignation would be appreciated so that a productive new member can be appointed and participate fully.

In any event, as long as you have quorum, the non-attending director is not a factor.