"E0695 The type in a dynamic_cast must be a pointer or reference to a complete class type, or void *" When replacing raw pointers with smart pointers [duplicate]

Hopefully I can solve this before someone else reply's to this, but for anybody who sees this I've got an error while trying to take a bunch of raw pointers and replace them with smart pointers. I've pasted my snippet of code below. The error appears around Ref on the 13th line if you're wondering.

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Matrix4 Actor::GetModelMatrix() { Ref<TransformComponent> transform = GetComponent<TransformComponent>(); Matrix4 modelMatrix; if (transform) { modelMatrix = transform->GetTransformMatrix(); } else { modelMatrix.loadIdentity(); } if (parent != nullptr) { /// <== LOOK AT IT! Think! modelMatrix = dynamic_cast<Ref<Actor>>(parent)->GetModelMatrix() * modelMatrix; } return modelMatrix; }