Hello Mr. Selmir,
This representation mean that the length you want to create is not taken in consideration by the rules (see attached print screen) you attempt to use. I suggest you to use an existing bolt like the A325 of another diameter to create your new bolts. If you are looking for the A307 3/8" bolts you can call us at support we already have them implemented in a spread sheet that you can copy direcly in the databases.
Attachment: Bolts Rules.jpg