Nastran:LOWER TRIANGULAR FACTOR HAS DIAGONAL TERM = 0

[kashm]

Hello Guys!

I got the following warning Msg. Does any body have an idea what does it exactly mean and how to fix it.
I know Mode shapes should be Independent. But I don't know how to fix them If the are dependent.

Waiting for your tips!
Thanks a lot!

^^^ USER INFORMATION MESSAGE 9037 (RESVEC )
^^^ CHECKING RESIDUAL VECTORS FOR LINEAR INDEPENDENCE.
*** SYSTEM WARNING MESSAGE 6731 (SDCBOD)
ROW 3 OF LOWER TRIANGULAR FACTOR HAS DIAGONAL TERM = 0( OR .LT. 0 IF CHOLESKY )

*** SYSTEM INFORMATION MESSAGE 4214 (SDCBOD)
1.0E-10 SUBSTITUTED FOR DIAG. TERM OF LOWER TRIANGULAR FACTOR AT ROW 3
*** SYSTEM WARNING MESSAGE 6731 (SDCBOD)
ROW 4 OF LOWER TRIANGULAR FACTOR HAS DIAGONAL TERM = 0( OR .LT. 0 IF CHOLESKY )
*** SYSTEM INFORMATION MESSAGE 4214 (SDCBOD)
1.0E-10 SUBSTITUTED FOR DIAG. TERM OF LOWER TRIANGULAR FACTOR AT ROW 4
*** USER INFORMATION MESSAGE 4158 (SDCBOD)
STATISTICS FOR SYMMETRIC DECOMPOSITION OF DATA BLOCK MZZ FOLLOW
MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL = 1.0E+10 AT ROW NUMBER 3

^^^ THE FOLLOWING MODE SHAPES (EIGENVECTORS OR RESIDUAL VECTORS) ARE NOT LINEARLY INDEPENDENT WITH OTHER MODE
SHAPES AND WILL BE DISCARDED.
^^^ MZZ MATRIX DIAGONALS/FACTOR DIAGONALS,RESVRAT= 1.000000E+08
0 BIGRATS
POINT VALUE POINT VALUE POINT VALUE POINT VALUE POINT VALUE
COLUMN 1
3 H 1.00000E+10 4 H 1.00000E+10

*** USER INFORMATION MESSAGE 5458 (REIG)
QL HOUSEHOLDER METHOD IS AUTOMATICALLY SELECTED .
^^^ FREQUENCY LIST OF SCALED COMPONENT MODES FOLLOWS.