Hi,
I am assuming you are using the Sybase.AdoNet#.AseClient driver for connectivity. I could be your batch size setting or something similar to that. We did have some issues with implementation of the ado.net driver but we have since cleared them up.
Please use SDK 15.7 SP100 or later of the SDK for SAP ASE.
Also are you using EnableBulkLoad in the connection string?
ref: SyBooks Online
Thanks,
Dawn Kim