This question comes up frequently and tends to stem from a misunderstanding of the interface. For activities where you listen to an audio clip and drag phrases into the order they are mentioned, once you submit your activity, you either get credit (if you were correct) or no credit (if you were not). If your answer was incorrect, you can click the View Questions button. This is where a misunderstanding can happen. What you see displayed is the correct order of the responses -- not what you just submitted! Some of the phrases will be highlighted in red. This indicates which items you had incorrect in your last answer submission. To get the answer correct, you can simply replicate the order as displayed in your next answer submission.
As an example, here is a test activity. The answers should be ordered from lowest to highest. You can see these answers are not in the correct order.
After clicking Finish Activity, of course credit was not awarded for the response "3, 1, 2, 4." Here is what it looks like after clicking View Questions: the correct order is displayed, with a red highlight around the items that were incorrect in the answer submission.