build spring element with force-displacement curves

dear all

        I build a spring element with CBUSH element, define the force-displacement table with PBUSHT. But when I run the analysis, there was an error come out.

ERROR: 

 *** See next message about line 91 from file:
     C:/Users/A044045/Desktop/rubber/rubber.fem
  'PBUSH          1'
 
 *** ERROR # 1000 *** in the input data:
 Incorrect data in field # 3.

 And I define the CBUSH and PBUSHT cards as follows. How could I correct the error? Thanks!

CBUSH          2               1       2                               1

PBUSH          1
PBUSHT         1      KN       2       1       2