a.Are you not able to see the logon in  "Sales Invoice"

b.Attach the logo in Company Info.

a. If you have only captured the Logo in company info option. This will not feature in your sales invoice.

Please use the following option 

Account and Setting > Sales (at left)>Customise look and feel > Standard> Edit> Make Logo Edits > "Show Logo"

b. Please verify the size of Image . You can use snipping tools to reduce the size of image.

Regards,

N.KEJRIWAL & CO.

Chartered Accountants