Investigation #4 Again

dgregory_58, welcome to the Fish Pond. The bottle does go back to it's original position after you use it. Is there liquid in the bowl? If not, click on water bottle again. This time, make sure the point of the cursor is on the bowl ... not the water bottle. I think if you put the bottle on the bowl, the cursor is outside of the bowl and when you click, it's not recognized.
...Good Luck

dgregory, when all ingredients are in the bowl, the task of creating the insecticide is complete and the item should be crossed off the list. If it's not crossed off, check to be sure you added all of the ingredients.
...then all you need to do is find the rest of the items on the list. Good Luck

You don't have to actually put the mixture in the spray bottle. Once you have all the ingredients in the bowl, the game will put it in the sprayer for you. I started with the water; don't know if that makes a difference.

Order of the ingredients does not make a difference. Check the recipe list on the wall to make sure all ingredients have been checked off. Then make sure all items in the list have been check off. If the fertilizer has not been checked off, double check the recipe board.
...You do not put in sprayer...the game does that once every item is in the bowl. And, it will then cross off the item on the main item list.