Need help disconnecting gas hose

I purchased a hose to convert and LPG heater to natural gas.  However, I'm not able to loosen the fitting (nut) which connects the current hose to the heater. Can anyone offer any advice on where I can go to have this done?

is it just too tight?  do you just need someone stronger? would wd40 help?

is it rusted?  The fitting holding my car battery in was so rusted and warped it had to be cut off.

jmitw said:

is it just too tight?  do you just need someone stronger? would wd40 help?

is it rusted?  The fitting holding my car battery in was so rusted and warped it had to be cut off.

 Thanks.  It's brand new; just incredibly tight.  I did use something similar to WD40, but it just won't budge.

Is it possible that it's reverse threaded?