Minitab ANOVA question

Hi guys

I'd really appreciate your help.

I am working on an analysis in Minitab and have run my normal plot of effects in order to tell me which factors are significant. Let's say a b c a*b.

I then plug these factors into an ANOVA in order to confirm that they are significant. When I do this I notice that my ANOVA has a 'lack of fit =3' and a 'pure error = 8' . I have never seen this before when I have run an ANOVA and I don't know what it means.

Can someone explain to me what it means or what it is saying about my model.i have tried textbooks etc but can't get a simple answer.

I'd really appreciate some help as I am going nuts here!!

Many thanks