Counter Output NI sample code not working..

[ByeongUk]

Hi, 

I tried to run a sample program given in the following directory,

\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Counter\Generate Pulse\Dig Pulse Train-Cont-Buff-Implicit,

which is a buffered pulse output program with pre-determined duty ratios.

However, an error says that the counter writing function cannot be started before the task is started.

I am using USB-6281 M-series DAQ. Is this sample program not suitable to my device?

How can I then use such pre-determined duty arrays or real-time duty updates?

I am really looking forward to hearing from you..

Thank you.

Byeong-uk, Im.