5. Trust of immovable property.—No trust in relation to immoveable property is valid unless declared by a non-testamentary instrument in writing signed by the author of the trust or the trustee and registered, or by the will of the author of the trust or of the trustee. Trust of moveable property.—No trust relating to movable property is valid unless declared as aforesaid, or unless the ownership of the property is transferred to the trustee. These rules do not apply where they would operate so as to effectuate a fraud.