#263 Error during OptiStruct run

Error:

A fatal error has been detected during input processing:

  *** ERROR # 2023 ***

  ADAMS MNF file creation requires DTI,UNITS card.

 *** Run terminated because of error(s) in the input data.

Solution:
You need to add DTI UNITS card.
Go to Control cards>> DTI_UNITS>> input the same unit system which you have used for modeling and run the analysis.