The test screen adopts what you have defined in the models, so do you have a window defined that is also using channel 1 ('Window 2') ?
Otherwise , the test tab should have said 'TREE" for channel 1.
You can check for overlaps on the layout screen - there is a checkbox there to be enabled and if u click on each model it will turn red if there is an overlap and the others will show yellow.
Otherwise , for each model that you have defined - enter the start and end channels in a spreadsheet , none of them should overlap.
Another option : create a new sequence and add the 'window 2' model that has channel 1 in it to it only , drop a 4 second color , click output to lights and that should light up.
You need to change the TREE model to start on a different channel number (than 1) is my guess.