[Closed] node->GetTMController()->GetPositionController()->GetValue get strange value

Hello all, here’s my problem:
I use node->GetTMController()->GetPositionController()->GetValue(time, &pos, FOREVER) to get the position of the referenced objet in NotifyRefChanged function
when message==REFMSG_CHANGE and partID&PART_TM_CHAN==true.

And I print the position whenever NotifyRefChanged is called.

if I move the object in x-axis, position is right.
But if i move the object in y-axis, y position that I get is not changed.
And if i move the object in z-axis, most of z position are right,
but z position will strang at intervals.

To make it clearer

original state : X = 0 Y= 0 Z= 0

I move object in x-axis, print as follows:
x, y ,z
0, 0, 0
1, 0, 0
2, 0, 0
3, 0, 0
It’s ok.

Then I move object in y-axis:
3, 0, 0
3, 0, 0
3,0, 0
y did not change.

Then I move object in z-axis, y changed to the right value, print as follows:
3, 3(ok), 0
3, 3, 1
3, 3, 2
3, 3, 3,
3, 3, 5,
…
3, 3, 10,
3, 3, 11,
3, 3, 0(become the value before i move in z-aix)
3, 3, 13(or greater)
3, 3, 14
3, 3, 15