Ethernet and eth driver problem

Hi, I am facing issue with opening any bearer(UART Bearer, GSM, Ethernet bearer etc).
/* Open the UART bearer */
bearerRet = wip_bearerOpen ( &br, PPP_BEARER, cbEvhBearer, NULL );

It is returning -44. I dont know -44 does mean.

I got to know that To open, configure and start the related bearer first the driver has to be registered with the wip_drvSubscribe () API. But i did not get any information regarding this API wip_drvSubscribe ().
Please let me how to subscribe to driver and how to open bearer. Thank you.