Error creating custom properties

Dear Sirs,
I just bought and installed Custom Properties Version 2.3.6 (2013-02-06).

When I try creating a new Custom Property I get this error:

Error while saving: TableCpfield: :store failed - Unknown column 'required' in 'field list' SQL=INSERT INTO `currao_custom_properties_fields` (`id`,`name`,`label`,`field_type`,`modules`,`published`,`required`,`access`,`ordering`) VALUES ('0','continente','Continente','select','88','0','0','1','1')

What am I doing wrong?
Thank you for your precious support.
Emanuele

It appears that the installation process has had some issues. More likely than not there was an older version of Custom Properties (for J! 1.5.x) already installed.

Could you please confirm if our guessing is correct?

Yes! It worked and I think your guess to be correct.
I had installed a previous version (the one for J 1.5) and it didn't work, but I didn't see it among the installed components, so I could not uninstall it (I thought it didn't affect the system).
Once I installed the new version, it didn't work, but it showed up among the installed components, so I could uninstall it and re-install the correct version.
Now it seems to work.

Thank you for your helpful support.
Emanuele

Glad it works now.

The problem stemmed from the fact that older versions of Custom Properties for J1.5 had different DB structure than newer ones.

In case you need to upgrade other installations from J1.5 to J2.5, please be aware that there's a procedure to do it properly:
solidsystem.it/how-to-and-tutorials/149-...es-to-joomla-17.html