Fedex property error

Opencart Version 2.0.3.1

when I put all the key, password, meter, account into fedex module, at checkout I get Trying to get property of non-object line 158

Does anybody have solution? if it is fixed in the newest version, how do you upgrade just the fedex module?

hello
anybody have any solutions?

sorry, there's others here also having problems getting fedex to work, but a little different than yours. I haven't figured mine out yet though.