Asset Inventory - Cannot Edit Last Inventory Date

I'm starting a fixed asset audit process, and in so doing would like to be able to record the most recent inventory date in each asset's SAP listing.  In transaction AS02, the field is greyed out for any assets that are not listed as assets under construction.  My assumption is that the asset class is preventing the 'Last Inventory On' from changing for completed assets, but not for assets under construction.  Where would I find the options for allowing that field to be altered?

Thank you,

William