Numerous reasons including:
1. Weak central government, all power in the hands of the state governments
2. Couldn't collect taxes
3. Couldn't regulate interstate commerce
4. Needed 9/13 to pass laws
5. Needed all 13 states to pass an amendment, difficult for everyone to agree
6. Couldn't raise an army
7. No President to run things
8. States didn't have to respect treaties of the central government
