Get GPRS using Osmocom and UmTRX

Hello, list. My hardware is Umtrx v2.1 and I have already built GSM components: Osmo-trx (branch fairwaves/master) libosmocore (branch: master) libosmo-abis (branch: master) libosmo-sccp (branch: master) libosmo-netif (branch: master) openBSC (branch: fairwaves/master, I use OsmoNITB) osmoBTS (branch: fairwaves/master. Also did ./configure --enable-trx at the installation process) So now SMS and calls work fine. Then I want to get GPRS up. I use master branch of openggsn and master branch of osmo-pcu (osmo-sgsn is supplied with osmoNITN). But when I start osmo-pcu, it says: "PCU interface version number of BTS (5) is different (7). Please re-compile!". After that osmo-pcu aborts. Could you please tell me what branches to use for correct work of GPRS?