Abaqus verification

Hello everyone
I have a question about Abaqus verification for a Mooney-Rivlin
hyperelastic material example which exist in ABAQUS Documentation/Abaqus
Verification Manual/2.2.1 Elastic materials/VIII. Hyperelasticity with
Mooney-Rivlin strain energy function. In the example for a Test data
input-uni axial tension the company Defined a stress-strain curve as
input for material property(Nominal stress-Nominal strain). But when I
plot these parameters(Stress -nominal strain) as output of the software
the result shows a significant difference between Input data and out put
data,and I don't know why?!
Any comment about this will be highly appreciable
this is the input file which I'm discussing about:
*HEADING
- COMPR. HYPEREL. (MOONEY-RIVLIN), TEST DATA INPUT, UNIAXIAL TENSION
*NODE,NSET=ALL
1,
2,1.
3,1.,1.,
4,0.,1.,
5,0.,0.,1.
6,1.,0.,1.
7,1.,1.,1.
8,0.,1.,1.
*NSET,NSET=FACE1
1,2,3,4
*NSET,NSET=FACE2
5,6,7,8
*NSET,NSET=FACE3
1,2,5,6
*NSET,NSET=FACE4
2,3,6,7
*NSET,NSET=FACE5
3,4,7,8
*NSET,NSET=FACE6
4,1,8,5
*ELEMENT,TYPE=C3D8RH,ELSET=ONE
1,1,2,3,4,5,6,7,8
*SOLID SECTION,ELSET=ONE,MATERIAL=MOONEY
*MATERIAL,NAME=MOONEY
*HYPERELASTIC, MOONEY-RIVLIN, TEST DATA INPUT
*UNIAXIAL TEST DATA
1.5506, 0.1338
2.4367, 0.2675
3.1013, 0.3567
4.2089, 0.6242
5.3165, 0.8917
5.9810, 1.1592
6.8671, 1.4268
8.8608, 2.0510
10.6329, 2.5860
12.4051, 3.0318
16.1709, 3.7898
19.9367, 4.3694
23.4810, 4.8153
27.4684, 5.1720
31.0127, 5.4395
34.5570, 5.7070
38.3228, 5.9299
42.0886, 6.0637
45.6329, 6.1975
49.3987, 6.3312
53.1646, 6.4650
56.9304, 6.5541
64.2405, 6.6433
*BIAXIAL TEST DATA
0.9384, 0.0200
1.5900, 0.0600
2.4087, 0.1100
2.6220, 0.1400
3.3240, 0.2000
4.4278, 0.3100
5.1830, 0.4200
6.6024, 0.6800
7.7794, 0.9400
9.7857, 1.4900
12.6351, 2.0300
14.6804, 2.4300
17.4000, 2.7500
20.1058, 3.0700
22.4502, 3.2600
24.6530, 3.4500
*PLANAR TEST DATA
0.6000, 0.0690
1.6000, 0.1034
2.4000, 0.1724
3.3600, 0.2828
4.2000, 0.4276
6.0000, 0.8483
7.8000, 1.3862
9.6000, 2.0000
11.1200, 2.4897
12.9600, 3.0345
14.8800, 3.4483
16.5800, 3.7793
18.2000, 4.0621
*VOLUMETRIC TEST DATA
60., .9703
118.2,.9412
175.2,.9127
231.1,.8847
*STEP,NLGEOM,INC=20
UNIAXIAL TENSION
*STATIC,DIRECT
1.,20.
*BOUNDARY,OP=NEW
FACE1,3
FACE3,2
FACE6,1
FACE4,1,1,5.
*EL PRINT,F=10
S,
E,
*NODE PRINT,F=10
U,RF
*EL FILE,F=10
S,E
*NODE FILE,F=10
U,RF
*END STE