Product:
Cognos TM1
Cognos BI
Windows 2008 R2 server

Symptom:
Can not apply formatting in active forms for TM1.

Solution:
Before installation of TM1, you need to install Microsoft Excel on the TM1 server to make Tm1web work.
Active Forms formatting does not work if you have a language specific Excel version, you must install a Microsoft Excel Multilanguage version.

Recommend that to any Tm1 installation, always install the Microsoft Office multi language versions of Excel 2010.