Most validation is done at the client, without any interaction with Helix. Dismiss the JavaScript Alert and correct the Issue Date. Click the Submit button again. If the data passes the validation, Osmosis will then check the script for errors. Each step is checked.
Osmosis checks each script step each time the script is called.
If an error occurs, a screen similar to the one shown below will be displayed. Osmosis will tell you what and when the error occurred. You must correct the error before you can continue. This just means that the target machine could not be found or is incorrect. The error shown means the target collection name was wrong or misspelled.