generating analog signal using usb 6008 DAQ Card

Hello,

After following the document Signal Generation Using NI-DAQmx for generating an analog signal of variable voltage and duty cycle. I wanted to send a simulated signal of ni express through ni usb 6008 daq card.

But unfortunately its not working. the Error i am having is in timming daqmx vi.

i therefore need guidence how to solve this issue.

i shall be very thankful to you.