Hi,
Looks like there is an issue with your Cava install.
Uninstall Cava. Delete anything left behind in install directories (their should not be - but something appears to be wrong)
Re-install Cava.
I have tested loading SpreadSheet::WriteExcel with ActivePerl 1007 using both current Cava 2.0.42 and your version 2.0.40. All seems to work OK.