Electronic – LTSpice .DC syntax error

I got this error

Syntax error in .DC command.
expected sweep starting value of source 'sweep'

I have no idea about how the syntax works. I only resorted in asking this site because it was urgent

And here is the code in question:

FILE: p-Enhancement ISFET Model
*********************************************************
*------     ISFET MACROMODEL     -------*
*********************************************************
.PARAM
*-------------------------------------------
*   Constants and common parameters
*-------------------------------------------
* k =   Boltzmann constant          [J/k]
* T =   Actual absolute temperature.        [K]
* q =   Electronic charge           [Coulomb]
* eps0  =   Vacuum dielectric permittivity      [F/m]
* epsw  =   Relative permittivity of the bulk (diffuse layer) solution
* NAv   =   Avogadro constant           [1/mole]
* Lisfx =   Gate length             [m]
* Wisfx =   Gate width              [m]
* Agate =   Gate area               [m**2]
* Cbulk =   Electrolyte concentration       [mole/l]
* Ka    =   Positive dissociation constant      [mole/l]
* Kb    =   Negative dissociation constant      [mole/l]
* Kn    =   Dissociation constant for amine sites   [mole/l]
* Nsil  =   Silanol (or oxide) surface site density [#/m**2]
* Nnit  =   Amine surface site density      [#/m**2]
* Eabs  =   Absolute potential of the standard hydrogen electrode   [V]
* Erel  =   Potential of ref-electrode(Ag/AgCl) relative to H electrode [V]
* Phim  =   Work-function of metal back-contact/electronic charge   [V]
* Philj =   Liquid-junction potential diff. between ref-sol. and electrolyte [V]
* Chieo =   Surface dipole potential        [V]
* Eref  =       (Eabs+Erel-Phim+Chieo+Philj) acts for gate-source ISFET Voltage [V]
*-----------
+   conv=1e3        conv2=1e6
+   k=1.38e-23      eps0=8.85e-12       T=300
+   q=1.602e-19     NAv=6.0221415e23    ET='q/(k*T)'
+   PI='355/113'        PI2='2.0*PI'

+      Nsil=1.0e18  Nnit=9.0e17         ;Si3N4
+      Ka=15.8          Kb=63.1e-9  Kn=1e-10    ;Si3N4
*+     Nsil=8.0e18  Nnit=0.0            *Al2O3
*+     Ka=12.6e-9   Kb=79.9e-9  Kn=0.0      *Al2O3
*+     Nsil=1.0e18  Nnit=0.0            *SiO2
*+     Ka=15.8          Kb=63.1e-9  Kn=0.0      *SiO2
*
+      epsw=78.5    epsihp=32   epsohp=32
+      dihp=0.1n    dohp=0.3n   Cbulk=150m
+      Eabs=4.7     Phim=4.7    Erel=0.205
+      Chieo=3e-3   Philj=1e-3
+      Lisf1=8u     Wisf1=30u   Agate='Wisf1*Lisf1'

+      bb='sqrt(8*eps0*epsw*k*T)'
+      Cb='NAv*Cbulk*conv'
+      KK='Ka*Kb*conv2'
+      Ch='(Agate)*((eps0*epsihp*epsohp)/(epsohp*dihp+epsihp*dohp))'
+      Cd='(Agate)*(bb*ET*0.5)*sqrt(Cb)'
+      Ceq='(1/(1/Cd+1/Ch))'
*
**************************************
***      MOSFET MODEL             ***
**************************************
*  ENHANCEMENT-MODE P-MOSFET
*-------------------------------------
.MODEL MISFET PMOS  LEVEL=2
+   PHI=0.7     TOX=39n     XJ=0.20u    TPG=1
+   VTO=-0.98   DELTA=2.9   LD=58.7n    KP=1.68e-5
+   UO=189      UEXP=0.24   UCRIT=1.15e5    RSH=0.1
+   GAMMA=0.64  NSUB=9.86e15    NFS=1.47e11 NEFF=1.5
+   VMAX=10.0e5 LAMBDA=4.25e-2
+   CGSO=0.185n CGDO=0.185n CGBO=0.43n  CJSW=0.26n
+   CJ=3.40e-4  MJ=0.58     MJSW=0.31   PB=0.90
*
*****************************************************************
.SUBCKT        ISFET      1        6      2     3       4       101
*
Vref    1   10  {Eabs+Erel-Phim+Chieo+Philj}
*
Ceq 10  2   {1/(1/Cd+1/Ch))}
RCeq    10  2   1G
*
EP1 46  0   V = log(KK)+4.606*V(101)
RP1     46  0   1000G
EP2     23  0   V = log(Ka*conv)+2.303*V(101)
RP2     23  0   1000G
*
EPH    2  10  V = (Agate*q/Ceq)*(Nsil*((exp(-2*V(2,10)*ET)-exp(V(46)))/(exp(-2*V(2,10)*ET)+exp(V(23))*exp(-1*V(2,10)*ET)+exp(V(46))))+Nnit*((exp(-1*V(2,10)*ET))/(exp(-1*V(2,10)*ET)+(Kn/Ka)*exp(V(23)))))
RpH   101  0  1K
*************************************************************
MIS   6    2    3    4   MISFET     L='Lisf1'  W='Wisf1'
*
.ENDS         ISFET
****************************************
VpH 500 0          DC      7.3
Vds 450 0          DC     -2.5
Vgs 400 0          DC     -2.0
*
****************************************
*
XIS    400    450    430   0     0    500    ISFET
*
***********************************
.OPTIONS   list node post probe pathnum  itl5=200000  tnom=27 ingold=1
.DC VDS 0 -10 1E-2  SWEEP VGS 0  -2.5  0.5
.PROBE  DC I(Vds)
.OP
.END