If statement for data pre processing not working. Please can anyone figure this out

My code

I am pre-processing a raw excel file with start date ('sd' in code) and end date ('ed' in code) for certain tasks and I wrote an if code for a new list/column which shows the status of each task. Namely not started, on going and completed. And the obvious conditions being if sd is empty then task not started, if sd present but ed empty then task on going and if sd and ed both present then task completed. But only the condition for completed works. Im using spyder with python 3.8