[Solved]The problem of the Slider joint.

I want to make a simple X-Y table by using Slider joint.
The joint of the X-axis body is fixed on the world.(The parent body pointer of the function is NULL)
The other of the Y-axis body is fixed on the X-axis body.
But the Y-axis body can't move on the Y-axis only.
When the X-axis body moves, the Y-axis body swings in X-axis.

How do I set the Slider joint for my movement?(There is only my specified direction by using slider joint of two bodies.)

I found the answer of this problem.
It's the wrong setting that the pin of slider is far away from the Y-axis body.
When I set the pin at the Y-axis body's position, the Y-axis body doesn't swing with X-axis movement.