@Kflora I do more searching than posting usually here and most of the time can find a solution.
If you have not used the BL Tester to model your case creation then that would be a way to know you are calling the methods correctly and getting the result you want.
The first link from @MikeGross below has a complete Case creation bpm in it if you want to review one that works and model yours after it.
The second link is on EpicCare about Epicor resources. I find a lot of information searching the KB there.
I assume you already have the ICE and Customization guides for your version. If not those are on the EpicWeb site.
Greg
Posting with Case creation BPM
Epicor resources
https://epicorcs.service-now.com/epiccare?id=epiccare_kb_article&sys_id=99ad3414db7ea38c7a572a9b8a961975