Problem with the convergence of Mooney Rivlin model

Dear all ; Im trying to model an hyperelastic tissue using Mooney Rivlin (MR) model in Comsol. When I use parameter values that satisfies the stability condition (below), the software never converges. This problem also occurs when I use two terms model. For all the examples that I could find and that work the C10 and C01 were positives. Did anyone face the same problem with Comsol? Stability conditions for MR: C10=-0.2948[MPa] // C10+C01>0 C01= 0.3179[MPa] C20=0.0300[MPa] /// C20+C02+C11>0 C11= 0.0715[MPa] C02 =-0.0973[MPa] /// C02<0 K = 0.4616[MPa] Regards