Summer using CFOA not working

I have designed a summer circuit using CFOA in Pspice,but its not working.The code is given below:


.SUBCKT CFOA 1 2 3 13
M1 11 10 6 6 NMOD W=10U L=1U
M2 10 10 6 6 NMOD W=10U L=1U
M3 11 2 12 12 PMOD W=74U L=1U
M4 10 1 12 12 PMOD W=74U L=1U
M5 4 4 5 5 PMOD W=74U L=1U
M6 12 4 5 5 PMOD W=74U L=1U
M7 1 4 5 5 PMOD W=74U L=1U
M8 13 4 5 5 PMOD W=74U L=1U
M9 7 4 5 5 PMOD W=74U L=1U
M10 3 4 5 5 PMOD W=74U L=1U
M11 3 8 6 6 NMOD W=10U L=1U
M12 9 9 6 6 NMOD W=10U L=1U
M13 9 3 7 7 PMOD W=74U L=1U
M14 8 13 7 7 PMOD W=74U L=1U
M15 8 9 6 6 NMOD W=10U L=1U
M16 13 11 6 6 NMOD W=10U L=1U
M17 1 11 6 6 NMOD W=10U L=1U
IO 6 4 10UAMP
V5 5 0 DC 0V
V6 6 0 DC 1.5V

.MODEL NMOD NMOS ( LEVEL = 3
+ TOX = 5.7E-9 NSUB = 1E17 GAMMA = 0.4317311
+ PHI = 0.7 VTO = 0.4238252 DELTA = 0
+ UO = 425.6466519 ETA = 0 THETA = 0.1754054
+ KP = 2.501048E-4 VMAX = 8.287851E4 KAPPA = 0.1686779
+ RSH = 4.062439E-3 NFS = 1E12 TPG = 1
+ XJ = 3E-7 LD = 3.162278E-11 WD = 1.232881E-8
+ CGDO = 6.2E-10 CGSO = 6.2E-10 CGBO = 1E-10
+ CJ = 1.81211E-3 PB = 0.5 MJ = 0.3282553
+ CJSW = 5.341337E-10 MJSW = 0.5 )


.MODEL PMOD PMOS ( LEVEL = 3
+ TOX = 5.7E-9 NSUB = 1E17 GAMMA = 0.6348369
+ PHI = 0.7 VTO = -0.5536085 DELTA = 0
+ UO = 250 ETA = 0 THETA = 0.1573195
+ KP = 5.194153E-5 VMAX = 2.295325E5 KAPPA = 0.7448494
+ RSH = 30.0776952 NFS = 1E12 TPG = -1
+ XJ = 2E-7 LD = 9.968346E-13 WD = 5.475113E-9
+ CGDO = 6.66E-10 CGSO = 6.66E-10 CGBO = 1E-10
+ CJ = 1.893569E-3 PB = 0.9906013 MJ = 0.4664287
+ CJSW = 3.625544E-10 MJSW = 0.5 )

.ENDS

X1 1 2 3 4 CFOA
R1 17 1 15K
R2 18 1 15K
R3 4 19 15K
R4 3 5 5K
V19 19 0 DC 1V
V2 2 0 DC 1V

X2 5 6 7 8 CFOA
V7 6 0 DC 1V
R5 8 20 5K
V20 20 0 DC 1V

Va 17 0 AC 10V
Vb 18 0 AC 10V
.AC DEC 100 100HZ 100KHZ
.PROBE
.END