Radar Relay moved from the old WETH contract to the new canonical WETH contract on January 8th 2018. Any WETH wrapped by the previous WETH contract will need to be unwrapped and rewrapped in the new WETH contract. There will be a prompt on your account page to unwrap the old WETH.
Navigate to the account page by clicking on the icon in the upper right.
The unwrap old WETH field will automatically populate with all of the old WETH you have.
Click unwrap and set the gas price to unwrap all WETH selected.
In the even that this prompt does not show up on your account page you can also unwrap old WETH on the 0x Portal.
Make sure your Metamask or Ledger is connected and use the portal at the bottom of the page to unwrap any old WETH.
You will need to confirm this action using Metamask or Ledger.