Ghosting problem on TN display

Hi,

We have a design for a custom LCD.  Our supplier have build many samples with different operating voltage but we still see a ghosting problem with it.  By ghosting, I mean we see Off segments when looging at angles not too much outside the optimal view range (from top or bottom).

It's a TN Transflective glass.  The drive D.C. is 1/8 with 1/4 bias.  It has 8 common and 22 segments.

The LCD manufacturer tried to solve this issue by finetuning the Operating voltage, but it did not really solve the issue.

The question: What could cause this weak viewing of the LCD? 
   Is the number of common (8) too high for TN display? 
   Could this be caused by an improper drive method?
   Is there another type of crystal (HTN for example) that could improve the view angle without too high impact on cost?

Thanks