Dear Karolina:
Wich version of SUM are you ussing? i recomend you the 1.0 SP13
on sybase please constantly reviewthe file SID.log on the directory /sybase/MEP/ASE-15_0/install
this log file show if the database needs more locks, memory , open partitions, etc.
Try to check on the SE11 the table if exist on the database and if you can adjust.
Regards