XML Schema Validation Errors

Question

Hey! I'm trying to upload my manifest.xml package to the Microsoft Office Store for my Excel add-in, which has a CustomTab based ribbon for added user functionality. However, I get the following error: Package acceptance validation error: XML Schema Validation Error Error found during XML Schema validation. Error code: The element 'CustomTab' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides' has invalid child element 'Label' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides'. List of possible elements expected: 'Group, OfficeGroup' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides'.

This is because there is a Label after my CustomTab tag opens, but without that Label, the Add-in ceases to sideload - is that normal? I've tried putting in a dummy placeholder group, but the sideloading still doesn't work, and I've also tried putting the Label in the first Group declared