Error #533 Composite Size Analysis

Hi,

 

I have been working on a laminate for a Formula SAE chassis with an optimisation approach in optistruct. 

 

Currently I am stuck at the beginning of the continuous size solve. After editing my plys and adjusting the stack to a manufacturable laminate I have come across the following error: 

ERROR # 533  Repeated independent DESVAR on DLINK -2. 

 

I am unsure what could be the cause of this issue and any advice would be greatly appreciated. 

 

Thanks

 

Daniel