Feedback error

[cliff_dangers808]

I'm trying to leave feedback for the purchase of a sunscreen for my windshield.

This is what I wrote followed by the warning from Ebay. What exactly is wrong with what I wrote?

Tell us more

Tell us more about your feedback  I wish it were a little thicker but it's a good product. 24 characters left

Your Feedback comment contains prohibited words or Web addresses. Please revise your comment.

[pierrelebel]

change "but it's" to "but it is" and it will work.

The robot read four consecutive letters  and that is not acceptable

[momcqueen]

However is a good substitute for 'but'.