Thanks - I added the missing ) and it did at fix some issues.  The generated sequence doesn’t make much sense, perhaps because it’s not a sophisticated network - and maybe an encoder-decoder where both are recurrent would do better in this case.
The task I’m trying to do is a simple sequence generation.  I have a bunch of tweets which I use to train the network, and I want to essentially generate a tweet by feeding a <GO> token and have the network output the next word in the generated tweet (word-by-word, since I don’t want to impose a fixed length on the tweet for now – no 140 char limit for now) until an <END> token is reached.  Would you call that a seq2seq problem?  It’s not exactly a translation problem.