[R] How to apply SSfpl with binary data

[baba@muj.biglobe.ne.jp]

Dear R-help subscribers

Would you tell me how to apply SSfpl with binary data as below?
Unfortunately, there is not the EXAMPLE in help(SSfpl) for binary data but for quantitative data(Chick). 

V1: dose 
V2: log-transformed dose
V3: response (rate)

      V1         V2        V3
1  0.775 -0.2548922 0.1666667
2  5.000  1.6094379 0.8148148
3 10.000  2.3025851 0.5000000
4 20.000  2.9957323 0.6428571

I also attach the error message in R 1.5.1 in following.

> targan
      V1         V2        V3
1  0.775 -0.2548922 0.1666667
2  5.000  1.6094379 0.8148148
3 10.000  2.3025851 0.5000000
4 20.000  2.9957323 0.6428571
> targan.1 <- nls(targan$V3 ~ SSlogis(targan$V2, Asym, xmid, scal), data = targan)
Error in solve.qr(a, b, tol) : singular matrix `a' in solve

Best and Kind Regards,
Baba

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