why vbt cant explain paramagnetic nature of oxygen

Valence bond theory consider that the atomic orbitals overlap to form bonds and due to this electrons are paired in overlapping and it shows that dioxygen is a diamagnetic species. It considers bonding according to the lewis dot structure.
Oxygen has configuration - 1s^​2 2s² 2p⁴  , it has 2 unpaired electrons , and requires two electron to complete its octet. So, it shares two electrons from the other Oxygen atom.

From the above lewis dot structure it can be seen clearly that O₂ doesn't contain any unpaired electron and so according to it is diamagnetic. But in actual case it is not so.That's why it fails to tell about the magnetic properties of the molecules.Molecular orbital theroy can tell about the magnetic properties of the molecules.