Trying to write OPOS Line Display Service Object

I am a newbie in OPOS.

I am developing a service object for OPOS line display.
When trying to use it through the MonroeCS CO control
(OPOSLineDisplay.ocx, version OposCCOs-1_11_001),
Open gives code 104 (=OPOS_E_NOSERVICE), and
get_OpenResult() gives code 305 (=OPOS_OR_BADIF).

What these return codes really means ?

In Control Programmer's Guide
(OLE for Retail POS, Release 1.6)
this is said in page 18, item 5:
CLIP -->
... (This ensures that the Service Object supports at least the
minimum methods of a valid Service Object for the device class, before
calling any of its methods.)
CLIP <--

Do I have to do the event handling as well as all the methods ?

Thanks,
Esko Hujanen
Ebsolut oy
www.ebsolut.fi