Your code starts before writing. The error message suggests that you write before starting. (Note: you can still write new data after starting, you just need to write *some* data there before starting so the AO has something to generate when it starts.)
Once you fix this, you'll probably also run into a problem on the 2nd iteration for trying to start a task after it's already running.
The first write and the start should happen before the loop. Inside the loop, you can write new data if you like, otherwise the original data will just keep repeating. You should also stop the task after the loop ends. Have a look at the shipping examples for continuous analog output.
-Kevin P
CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
