I cannot see the data mining ribbon in Excel 2007
 

I encountered an issue when I install and configure Excel data mining add-in,
I cannot see the data mining ribbon in Excel 2007.

Analysis Service Server:
1) SQL server 2005 enterprise edition with SP3

Client:
1) Excel 2007 with .net programmable support
2) .net framework 3.5 SP1
3) Office 2007 Data mining add in published in Dec. 2008

Besides, the above installation, I
1) Configured the connection from data mining add-in to Analysis Service and
created databases, DMAddinsDB and DMAddinsDB2
2) Restart the server and my laptop after the installation and configuration
3) Searched the internet, didn't find a workable solution
4) Contacted service desk, they cannot provide help on this.

Known issue: two data mining com add-ins are active; but two excel add-ins
are inactive, but I dont know how to activate them.