COM-Add in requires reinstall to work

Hey guys,

I use an add-in to get data from an SAP type program into excel. I've been using it for a few year with office 2007 and I have never had problems with it. Recently we "upgraded" to office 2013 and now every time I want to use the add-in i have to reinstall it to work. When i start my doc the add-in is present in the add-in ribbon but if I click it nothing happens. So I have to go to file>option>add-ins uncheck it then activate it again in order to work. And if I close the file and open it again its the same. Any ideas, suggestions are welcomed.

Thanks.

any ideea is welcomed