SOAP API call returning EmptyStackException

Hi all,

I'm a beginner to SOAP so I thought I'd test the SOAP API in UCMDB using the simplest API call I could find using SOAP UI 4 (getCIsById).

But when I try to query using the global ID of my node in UCMDB I keep getting this (not particularly helpful) error message: "null; nested exception is java.util.EmptyStackException". You can see it in more detail in the attached screenshot.

Does anyone know what the problem could be?

I'm using UCMDB 10.20.

Regards, Hasan