Created Unassigned: dbgCommand stepping error [13701]

```
from pykd import *
print dbgCommand("t")
print dbgCommand("t")
```
in my think above code doesn't have any problem.
but i got this error message.
```
!py C:\Users\wa\Desktop\b.py
Traceback (most recent call last):
File "C:\Users\wa\Desktop\b.py", line 16, in <module>
main()
File "C:\Users\wa\Desktop\b.py", line 13, in main
stepi()
File "C:\Users\wa\Desktop\b.py", line 5, in stepi
print dbgCommand("t")
BaseException: IDebugControl::ExecuteWide failed
```
what's the matter??