I just install the application to my Dolphin7 website

After Universal Login, the signer gets the following error message

Fatal error: Call to undefined function bx_get() in /home/xxxxxxx/public_html/modules/boonex/rpx/classes/BxRpxModule.php on line 178

How Can I correct the error message?
Below is the legacy version of the Boonex site, maintained for Dolphin.Pro 7.x support.
The new Dolphin solution is powered by UNA Community Management System.