well I haven't played with dishnet for many years now, but based on what fn59 and Terryl said, I would go to lyngsat.com and find the transponder frequencies that are active on 118.7 (118.8) and make sure the SR (Symbol Rate) and FEC (Forward Error Correction) are correct.

if your receiver allows you to input the appropriate satellite and supports the SR and FEC then you should be good to go