LaserSoft Imaging

I am new to this forum so I hope I am posting in the right place.
Silverfast se was working fine with my Epson Perfection 2450 Photo scanner. I have been scanning my medium format negatives to get them into a digital file. Now all the scans are posterized. can anyone help me with this problem?
Downeast

Dear downeast,

there are several settings which could cause this.

Have you tried resetting the preferences?
That will reset the software and clear all settings which might be responsible.
http://www.silverfast.com/problemreport/en.html?filter=assistant&sub=techsupport&faq_id=59

kind regards,
Arne Ketelhohn.