Are you sure you are not banned from posting on Timeline, and this can happen even when the ban is partially lifted. Another option can be: In the Help Center, click on "Timeline"
Scroll down to "Bugs & Unknown Issues"
At the bottom of that page, there is a statement that says: "If the issue you're experiencing isn't listed above, please 'tell us more' <--Click on the "tell us more"
A screen says, Report an issue with timeline, click "other" Add your subject and/or details then click send.