Good app but have a problem

The quality of sound is very good.But
I have the problem with play Decibel after it was closed:
1. Open Decibel
OK
2. Select file
OK
3. Play file
OK
4. Stop play
OK
5. Close Decibel
OK
6.
Open Decibel
OK
7. Play file (which was remembered)
Not OK !!!
Decibel show the message
"This operation couldnt be completed.
Operation is not permited.»

OS El Capitan

pnn314 about Decibel, v1.3.3