Is there any other way to get LD50 for these cases when Probit does not yield results

#1
To determine a lethal dose 50 (LD50) (ie the dose or concentration of a compound that kills 50% of the insects) I have done a Probit regression. In some cases, the p square CHI is > 0.05 or the statistical programs for do Probit regression does not yield any result. This behavior does not change when I increase n, or I increase the number of doses, or when I normalize the data with LOG. The question is: Is there any other way to get LD50 for these cases when Probit does not yield results?
 

Dason

Ambassador to the humans
#2
Re: Is there any other way to get LD50 for these cases when Probit does not yield res

What does the p-value have to do with getting LD50?