What is wrong with my watermelon plants?

I started off several seeds in the little peatmoss kits you can buy at the store. I transplanted the plants several weeks after they started growing, and now they are in my garden and have been for a few weeks now. For some reason with my melons they appear to be wilting, especially with the watermelons. A few have died completely, and I have one now that looks like it is on the verge of death. There are no bug problems that I know off (I placed cardboard around the plants to protect them from cutworms), and I water daily. So my question is, am I watering too much? That is the only thing I can think of.