Linear order perturbation with XAct

[Pawan Kumar Gupta]

Hi,

I am trying to perturbed Einstein equation for Schwarzschild background 

metric, essentiality want to get Zerilli Equation. To do this,

I use Xpert to get first order perturbation equation, but when I use Xcoba to 

insert the metic and perturbation then it gives me error.

I have attached my Mathematica notebook.

Thank you for help in advance.

Best,

Pawan