Error while commucating with Excel. Xcelsius must close?

I am trying to open a xlf file and I get this message.

Error while commucating with Excel. Xcelsius must close?

I am running Xcelsius Engage 5.3.0.0

Is anyone facing the same problem? How can I solve it?

Thanks in advance for your help.

I am running Office 2007 and I cant activate or deactivate the Live Office Compatbility option ( File/Preferences/excel options)