Family Kept Nick Carter From His Sister's Funeral?

25-year-old Leslie Carter was laid to rest at a small ceremony in Upstate New York this weekend after a suspected prescription drug overdose. Several family members were present at the funeral, including Aaron Carter, but Nick was not.

Nick -- who was on the road performing at a concert at the time of the ceremony -- tells TMZ, "I wanted to be at my sister's funeral, but my family has always had a complicated dynamic."

Nick would not get specific about the circumstances ... but sources close to the singer tell TMZ ... he feels family members went out of their way to make sure he was not included.