JPA/Glassfish 3.0.1 java.lang.IllegalStateException: During synchronization

My class model contains a class that has relationship tagged with annotations. I took care to use them correctly by adding the famous "cascade=cascadeType.PERSIST". Sometimes it works, but, very often not, I get this error message :

"java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: Model.Donation[id=null]."

I found on several web sites that comes from the library but without more explication...

Thank you for your help

@OneToOne(optional=true, cascade=CascadeType.ALL)
private Localisation localisation;
@ManyToOne(cascade=CascadeType.ALL)
private Device device;
@ManyToOne(cascade=CascadeType开发者_如何学Go.ALL)
private Project project;

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As my relationships are bi-directional, I though I only need to set cascadeType to the relationship that manages the relation. But it isn't. By adding cascadeType.ALL to the both sides, it works perfectly!