Hi Mario,
I had this exact issue. I am using MS Excel 2010 32bit and MS Excel 2013 32bit. I suspect the solution will work for 64bit as well.
In your ODBC Data Source, there is a Settings Button for Advanced Setup. Inside the SAP HDB ODBC Advanced Setup screen: Add a Special Property for "SHOW_CATALOGS" with a value of "TRUE".
Hope that helps.
Dan