When there is an error or incomplete information on a page in your account, Sling will not allow additional changes to be saved. The button will appear grayed out.
Fortunately, Sling has a way to let you know where the issue is so that you can correct it!
When you notice that the Save button at the bottom of the screen is gray, go ahead and click it. You'll see that it registers your click because it will "roll up" to temporarily display an x before returning to its original appearance.
Now, look over the details on the page you're viewing and look out for a field that is highlighted (outlined) in red. This will indicate an error.
Common examples of errors are a blank field, unsupported characters (a period or decimal point is not supported), or missing details. These errors can happen when importing data on occasion.
Once all errors are corrected, you will notice the Save button is blue again.