Let $M$ be a compact manifold, the theorem of de Rham asserts that this is an isomorphism between de Rham cohomology and singular cohomology. Suppose that $M$ admits a smooth group $G$, where $G$ is a compcat Lie group. We can define the complex of $G$-invaraint forms with differential whose cohomology is denoted by $H^{*,G}_{dR}(M)$; and complex of $G$-invariant cochain with real coefficient, whose  cohomology is denoted by $H^{*,G}(M)$. 

I guess that $H^{*,G}_{dR}(M)\cong H^{*,G}(M)$.

**Q**  1. Did someone already show this, or its proof is exactly the same as the de Rham Theorem? (I can not image any obstruction)

 or

2. It is wrong, with a counter-example?