getRoleFillers problem - OWL API 3

[Dmitry Tsarkov]

Original [issue 50](https://code.google.com/p/factplusplus/issues/detail?id=50) created by dtsarkov on 2012-05-19T12:05:07.000Z:

Hello,

I'm using the latest version of Fact++ for Linux (version 1.5.3) together with the OWL API 3 (version 3.2.4). When I try to use a getObjectPropertyValues(individual, property) request to the reasoner, I get an exception with the message "Role expression expected in the getRoleFillers()". What is it caused from? What can I do?

Thanks for your time, Nicola

[Dmitry Tsarkov]

Comment [#1](https://code.google.com/p/factplusplus/issues/detail?id=50#c1) originally posted by dtsarkov on 2012-05-21T16:24:27.000Z:

Hmm, sounds strange. This exception happens when the property passed to a reasoner is either not of a property type, or null. Could you please add more details, like the used ontology and/or code that leads to the exception. I'll have a look.

[Dmitry Tsarkov]

Comment [#2](https://code.google.com/p/factplusplus/issues/detail?id=50#c2) originally posted by dtsarkov on 2012-05-21T22:16:57.000Z:

Ok, after reading your comment I checked whether everything was in place (prefix, names and so on) and I found out that a call to the "flush()" method was missing, as the property causing the problem was inserted without explicitly updating the reasoner. Now it looks like it's working. I haven't noticed this before because while using a different reasoner this was not necessary.

Do you have any comments about this? Anyway, may I suggest a slightly more informative message for the exception?

Thanks again, Nicola

[Dmitry Tsarkov]

Comment [#3](https://code.google.com/p/factplusplus/issues/detail?id=50#c3) originally posted by dtsarkov on 2012-05-27T14:34:13.000Z:

You might try to use NonBuffering reasoner instead of buffering one. I'll think about better wording of the error message.