VarD errors!

[NotoGrav]

Hello everyone,

I am trying to take VarD of an expression Lflat2 (please see the attached notebook). I converted g to eta metric for finding this expression. The VarD rules I have set as well. Here are the errors I am having.

VarD::nouse: Attempting to apply VarD on a non-scalar expression.

ToCanonical::cmods: Detected metric-incompatible derivatives {PD}.

General::stop: Further output of ToCanonical::cmods will be suppressed during this calculation.

Any suggestions/feedback how to resolve these issues?

Thank you.