Of course you have the guid of the activity (crmd_activity_h) right? Great, now through CRMD_LINK and CRMD_SRV_OSSET reach table CRMD_SRV_SUBJECT, yes here it is. And if you want to read the text, just read table QPCT too.
The GUID between tables CRMD_SRV_OSSET and CRMD_ACTIVITY_H are not corresponding!
CRMD_ACTIVITY_H contains over 2000 records, whereas CRMD_SRV_OSSET contains only around 100. A few random searches show that the GUIDs within CRMD_SRV_OSSET are not found in CRMD_ACTIVITY_H