Thread, WaitSleepJoin

Question

I start four threads after each other because I want them to run simultaneously, the problem is that they only run one at a time. The other threads has the state "WaitSleepJoin". Any idea why this could be? starting them with the code below, dThreads is an ArrayList: dThreads.Add(new Thread(new ParameterizedThreadStart(test))); string s = offset + ";" + (offset + partSize) + ";" + i; ((Thread) dThreads[i]).Start(s);