So just to test this, I went to the question ( DDL trigger permission Error ) and copied the text in the rendered code block (not the "raw" text from clicking on "edit", just to be clear), and will paste it below and add the word "AS":
CREATE TRIGGER [TR_CaptureDBChanges] ON DATABASE
FOR CREATE_PROCEDURE, ALTER_PROCEDURE,DROP_PROCEDURE,
I've occasionally had issues posting code that includes certain terms - for example, CREATE TABLE. In my case, I believe this was being blocked by a content filter at my place of employment - I was able to post the code successfully from home.
It's possible you encountered something similar.