Our overwrite period set to 4 weeks and append period set to 2 days. Lets understand how it works
Append Period : 5 days
Overwrite Protection Period: 1 day
Any media / TAPE using the Above Media set will append to the media / TAPE for 5 days and after the 5th day is over it will protect the media / TAPE for 1 day, this means that the Overwrite Protection Period starts AFTER the Append Period is OVER.
In our case the Overwrite Protection Period is 4 weeks and Append Period is 2 days, means the TAPEs will be protected for 4 weeks after the 2 days append period is over.
All the TAPEs allocated to the above media set are Overwrite protected as the append period is over and their is no TAPE associated with Scrateh media set.
Backup Exec will look if any media is appendable OR Overwritable first in the current media set, afterwords it will look in the Scratch Media Set, if no appendable OR overwritable media is found, it will throw the message "Please insert an overwritable media"
I think you should reconfigure Append period and Overwrite protection period.
If there are some TAPEs which are "Not Appendable" and no important data is on them, simple drag and drop them in "Scratch Media" making them re-usable.
Hope this will help !!!