There could be a few reasons for this:
1. Depending on where you posted it, your thread may need approving first. In this case you will be notified in due course. Please be patient as the moderators are very busy.
2. Your post or thread may have been deleted due to a rule violation - take a look at our Terms and Conditions.
3. It may be a known error that's being worked on, which will go away after a while. If the problem persists, please contact support.