In Rational Insight 1.1.1, Need to enable " view in excel sheet 2007 format" button

I expect you are clicking on a report view that has saved output, so when you click on that report you are taken directly into the saved report.  That saved report only has one output format, which is not Excel.  That is why the other output formats are greyed out.

If you instead "run the report with options" by clicking on the play icon on the far right of the report view, then you can select which output format you want to run the report for.  You have the option to "View the report now" or to "Save the report".  If you save the report with an output format of Excel, then when it is done, you can just click on the report view to go directly into Excel format.