# Shift data to use Gamma glm with “identity” link?

I am trying to fit a glm using the Gamma family and the "identity" link. As I am analyzing nutrient concentrations in coastal waters (that can not be negative and are unlikely to be zero) I assume the Gamma distribution would be suitable. There are no zeros and no negative values in the data. If I have more than one independent variable (year, site, dist, season) and interactions in the model

m1<-glm(din~year*site*dist*season,family="Gamma"(link="identity"),data=mydata)


I get this error :

Error: no valid set of coefficients has been found: