Gevrey local solvability in locally integrable structures

We consider a locally integrable real-analytic structure, and we investigate the local solvability in the category of Gevrey functions and ultradistributions of the complex (mathrm{d}^{prime }) naturally induced by the de Rham complex. We prove that the so-called condition (Y(q)) on the signature of the Levi form, for local solvability of (mathrm{d}^{prime }u=f) , is still necessary even if we take (f) in the classes of Gevrey functions and look for solutions (u) in the corresponding spaces of ultradistributions.