Most often, this happens when trying to request a 'new' or 'high demand' item that isn't owned by your local library (e.g. if you live in Marathon County, the item isn't owned by any MCPL location).
If you receive a 'No Items Requestable; Request Denied' message when trying to request an item, this is likely what is going on.
Your best options are to either find and request a different version of the item that is owned by your library, or if this is isn't possible, submit a purchase suggestion.
Other reasons your request may be denied:
The item is intended for use in the library only — e.g. item types of 'Reference,' 'Laptop / Computer,' 'AV Equipment,' etc. (as indicated in the 'Location' field).
It may be a 'Lucky Day' item that may only be checked out while at the library.
You may have already requested the item (check your account).
The only available item is damaged, lost, or otherwise unavailable (as indicated under 'status' in the item's record).
You have 75 other items already on hold or request (the account maximum).