R help - Oct 2013 - problem fitting 2 term exponential with nls

Hi,
Can anyone explain why the nls function is giving an error?
Thanks
Tom
> head(d)
        age  time
1 23.566667 223.0
2 42.633333 223.0
3 62.300000 222.0
4 32.933333 220.5
5  9.366667 228.0
6 23.833333 227.0
> fit<-nls(d$time~a1*exp(b1*d$age) + 
	a2*exp(b2*d$age)+c 
	,start(a1=10,b1=0,a2=250,b2=1,c=0)
	,trace=T)
Error in hasTsp(x) : argument "x" is missing, with no default

On 25-10-2013, at 17:29, Tom Wright <tom at maladmin.com> wrote:
> Hi,
> Can anyone explain why the nls function is giving an error?
> Thanks
> Tom
> 
>> head(d)
>        age  time
> 1 23.566667 223.0
> 2 42.633333 223.0
> 3 62.300000 222.0
> 4 32.933333 220.5
> 5  9.366667 228.0
> 6 23.833333 227.0
> 
>> fit<-nls(d$time~a1*exp(b1*d$age) + 
> 	a2*exp(b2*d$age)+c 
> 	,start(a1=10,b1=0,a2=250,b2=1,c=0)
This line should read:  start=list(a1=10,b1=0,a2=250,b2=1,c=0)

Berend
> 	,trace=T)
> Error in hasTsp(x) : argument "x" is missing, with no default
> 
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