hello, if your waste bottle is white and semi transparent, I recommend that once you have emptied (which you already did), you fist a hand (what you grab with a hand) of detergent powder, here in Mexico recommends the call Rome, or another called Seal or finally one called Snow White (they are precisely of the most economic), DO NOT GO TO ECHAR WATER, with the detergent inside, shake it and you will see that these detergents pull the dust toner is stuck on the walls of the boat, you have to do this because many teams have optical sensors to detect that the boat is empty, but if they "see" spotted, they find that it is still full and so it continues with the error. check this point and tell us. Atte. césar hernández