Error in robot simulink

Hello, i use matlab 2013 for simulating a model of robot with 3 dof. I get this error: "Error originates in Mechanical block x1/Revolute. The motion is singular (the mass matrix is singular). What is it mean and how can i solve the problem?

[Stéphanie Monteiro]

Did you solve the error?

I'm having the same error and I don't know how to solve this.

[zy geg]

Hello, I also encountered the same problem, may I ask if you have solved it? How to solve it? Thank you very much!