Problem of STS in NONMEM

Dear all, I got a problem when using NONMEM with STS method. My aim is to get individual parameter estimates. I would like to let NONMEM estimate individual parameter one subject by one subject. My control stream is partially listed below, which is edited according to this thread http://www.cognigencorp.com/nonmem/nmo/topic035.html *$SUBROUTINES ADVAN1 TRANS2* *$PK* *CL = THETA(1) * EXP(ETA(1))* *V = THETA(2) * EXP(ETA(2))* *S1 = V* *$ERROR* *IPRED = F* * W = F* * Y = IPRED*(1+EXP(ETA(3))*EPS(1))* * IRES = DV-IPRED* *IWRES = IRES/W* *$THETA* *(10,20,30) ; CL* *(10,80,100) ; V* *$OMEGA* *100 ; IIV CL* *100 ; IIV V* *100 ; IIV SIGMA* *$SIGMA* *1 FIXED ; PRO* *$EST METHOD=1 INTER MAXEVAL=0 NOABORT SIG=3 PRINT=1 POSTHOC* *$COV* *$TABLE ID TIME AMT CMT DV PRED IPRED IWRES CL V ETA(1) ETA(2) ETA(3) ONEHEADER NOPRINT FILE=sdtab101.tab* The model can run successfully, and I got individual parameter estimates from output file. I found that for each subject the individual parameter estimate changed if I change the initial value of THETA. It seems that NONMEM regarded the initial value fixed (just like a fixed typical value). But I expected NONMEM to estimate individual parameters based on individual data rather than the initial value. Is there anything wrong with the code? Thanks in advance. Anyue