it must be divisable by 1024 to meet the RFC.
Try these:
===
maxRecvDataSegmentLen=262144
MaxBurstLength= 1048576
Maxxmitdatasegment=262144
FirstBurstLength=65536
DataDigest=None
maxoutstandingr2t=8
InitialR2T=No
ImmediateData=Yes
headerDigest=None
(deprecated)Wthreads=8
===