You have not activated the connection in the booking.com extranet. Please log into your booking.com extranet and activate the connection.
'''SINGLE_USE_PRICING_PASSED_FOR_RLO_RATE or OBP_PRICING_PASSED_FOR_SINGLE_USE_RATEor INVALID_USE_OF_SINGLE_OCCUPANCY'''
Booking.com does not allow you to send a single price.
Set "Booking.com Rate Type"= Per Day Pricing