Robin Thicke -- Another Concert Canceled ... For The Beach

Robin Thicke went camping with his son and a mystery woman the same day he was supposed to be performing in Indiana ... and this isn't the first time it's happened.

What was termed a "scheduling conflict" was in actuality a personal day ... deja vu, because he did the same thing back in February when he cancelled 2 back-to-back concerts because of illness, but ended up at Disneyland in Anaheim, CA with his son.