From the OP:
The lightweight wallet does not currently support importing accounts it did not itself create. If you want to use it, you will need to register an account using the light wallet, via faucet.bitshares.org. The wallet will walk you through the steps.
@cass: Oops, my mistake. I didn't configure the server quite right after restarting it; sorry about that. The wallet should have worked anyways, and the features that need the new_assets aren't implemented yet, so it's a safe warning to ignore. Still, it should be fixed now.
@vlight: I'm not familiar with Electrum's security model, but the light wallet is, as far as I know, secure as long as the server can be trusted to provide accurate chain state information. Once I have a stable application and protocol, I'll be releasing instructions for others to set up servers and configuring the light wallet to get chain state from several sources. The high points are that the light wallet never releases private keys, it destroys the owner private key after you back up the master password it creates for you, and it creates transactions locally, then scans the transaction to show you the confirmation page, so it shouldn't ever make an unexpected transaction without showing it to you again on the confirmation page.
And yes, it needs a good name. Suggestions are welcome.