I am trying to generate invoices directly from my opportunity account..when I generate a quote and convert it to a PDF the tax amount I inputted comes up, however when I sync this to my account and then try and generate a quote and invoice through my main opportunities page, the tax is not there only my products. 
How can I add taxes to my invoices?

Thanks

I am trying to generate invoices directly from my opportunity account..when I generate a quote and convert it to a PDF the tax amount I inputted comes up, however when I sync this to my account and then try and generate a quote and invoice through my main opportunities page, the tax is not there only my products. 
How can I add taxes to my invoices?

Thanks