Question Type.GetField problem.

I'm writing a property drawer for a generic class, thus I need to know the generic type I'm editing, for that I'm using this code:

Code (CSharp):

1.  
2. Type      parentType = property.serializedObject.targetObject.GetType();
3. FieldInfo fi         = parentType.GetField(property.propertyPath,BindingFlags.NonPublic);
4. Type      t          = fi.FieldType;
5. if(t.IsGenericType) {
6.    parameters = t.GenericTypeArguments;
7. } else {
8.    parameters = new Type[0];
9. }

But it only works if the property is public and no BindingFlags are provided to GetField... I have tried everything I've thought of, but just can't make it work with private properties... any ideas?