How can I find sergio I'm at the tissue trail and I can't get through the..

You don't go through the door, the tissue trail is going off down the stairs in the other direction. The way you can tell you are close to having the magnifying glass in the right place is you will see the magnifying glass symbol on the right side of the screen and there will be a little bell sound. (look on the red carpet) After you first see the tissues on the ground you can put the magnifying glass away and they will stay visible. You follow them until they run out and then bring the glass out again and follow the next section of tissue. You will do this over and over, and be taken all over the Chalet and Howling Peaks. Good Luck!