Yes if you test too early you can get a negative result.
You can always search for things like that on Yahoo too..this is what i found on it:
Doctors use two types of blood tests to check for pregnancy. Blood tests can pick up
hCG earlier in a pregnancy than urine tests can. Blood tests can tell if you are pregnant about six to eight days after you ovulate (or release an egg from an ovary). A quantitative blood test (or the beta hCG test) measures the exact amount of hCG in your blood. So it can find even tiny amounts of hCG. This makes it very accurate. A qualitative hCG blood test just checks to see if the pregnancy hormone is present or not. So this test gives a yes or no answer. The qualitative hCG blood test is about as accurate as a urine test.
http://www.womenshealth.gov/faq/pregnancy-tests.cfm