Modal analysis with ACMS

[nabilishes]

Im running modal analysis and keep on getting this error. I have no idea where to check it. RBE2 and RBE3 in model seems fine. Dependency errors have been checked prior to the runs. And there is no flying items (unconncedted) in the model.
At executive control section i activated acms with the following command
DOMAINSOLVER ACMS (PRINT=NO, NUMDOM=512, UPFACT=3.0)

here is the excerpt of f06 file fatal error
^^^ -----------------------------
^^^ ACMS PHASE 1 BEGIN
^^^ -----------------------------
^^^
*** SYSTEM FATAL MESSAGE 9160 (SUBDMAP MDACMS)
PROBLEM ENCOUNTERED IN CALCULATING DOMAINSOLVER ACMS DOMAIN MODES.
USER ACTION: IF LARGE MASS IS BEING USED FOR ENFORCED MOTION THEN REPLACE LARGE MASS METHOD WITH DIRECT METHOD
USING THE SPCD BULK DATA ENTRY.
USER INFORMATION: IF THE LARGE MASS METHOD IS NOT BEING USED THEN MASSLESS MECHANISMS MAY EXIST.
PARAM,MECHFIX,YES MAY BE USED TO IDENTIFY MASSLESS MECHANISMS.

Anyone encountered this before?

 

[nabilishes]

I managed to solve this issue.
It is just the consistency in units between the model and the input header. The model was converted to units kg,mm,kN,GPA,ms according to work requirement guideline, however frequency in header was set in Hz. Converting the frequency unit s^-1 to ms^-1 solve this issue.