Prevent user from entering incorrect End Time

Hi,

Is there a way to create an error in the form if someone enters a end time that is before a start time? 

Esentially I have people submitting requests and forgetting to make sure that the end time is after the start time. 

For example- Start time is 1:00pm but then for end time they put 2:00 am which messes up my automation to my google calendar.

I can see that you already used a Form Calculation widget to identify the difference between the 2 time fields, which I am about to suggest too:

However, I think that the formula should be the other way, "End Time - Start Time". Then create a condition to show the "Cannot Submit" text when the value is a negative number, which means that the End time was set to "A.M". While if it's set to "P.M", it will return a non-negative number.

Here's the condition I came up with:

Here's a quick demo:

Please try this workaround and let us know how it goes.