Hi mrboffo555,
Thank you for using the Apple Support Communities! We understand you're trying to drag and drop a file from your Mac to an application online. We'd like to see how we can help, but there are a few questions we have as well:
What type of file is this?
What happens when you try dragging and dropping it?
Are you able to successfully drop it to other locations? In other words, is it just failing to copy to this online application you mention?
Did you try other ways to upload it to your application online other than drag and drop?
In the meantime, check out this resource: If you can’t move or copy an item on Mac
Best regards.