Barrier Statue of the Abyss and Barrier Statue of the Heavens -- A Contradiction?
No Monsters can be Special Summoned. Both Monsters have a Continuous Effect (page 14 of PDF) that is active while they are on the field. BSotAbyss blocks all non-DARK Monsters from being special summoned, so when you Attempt to Special Summon a DARK Monster, it is BSotHeaven that blocks you, and vice versa when you Special Summon a LIGHT Monster, it is BSotAbyss that blocks you.

This effect is active while the Effect Monster Card is face-up on the field. The effect starts when the face-up monster appears on the field, and ends once that monster is gone or is no longer face-up; [...]

The Barrier Statues prevent any Special Summoning, unless the Monster is of a matching Atribute (page 11).

Barrier Statue of the Abyss - No monsters can be Special Summoned, except for DARK monsters.
Barrier Statue of the Heavens - No monsters can be Special Summoned, except for LIGHT monsters.