[R] gam(mgcv) starting values

[Björn Stollenwerk]

Hi all!

I’ve got some problems with the function gam (library mgcv). For some 
models I get the error message :

Error: no valid set of coefficients has been found:please supply 
starting values
In addition: Warning message:
NaNs produced in: log(x)

This is a shortened code I used:

gam(y ~ M1 + M3 + M4 + M5 + M6 + sex + M1*M3 + s(age),
family=Gamma(link ="identity"),
weights=days)

If I add for example an additional variable, say M7, the error-message 
occures. If I add M7 in combination with for example M8 it works.

Does somebody know, how to supply starting values or how to handle this 
problem.

I didn’t suxceed by adding
control=gam.control(spIterType="outer"),
or by
sp=137722.1

Thank you very much,

Björn