Why do my oatmeal cookies come out soft and squishy?

I have made two good-reviewed oatmeal recipes this week. The second was from Martha Stewart's book and I followed it to the T. I am a pretty good cook - but every time I make an oatmeal raisin cookie they come out really flat and full of holes. They hardly stay together. What could be my problem? I am using Airbake cookie sheets. TIA