[a_in_scan gives result of "no connection established"]

Hi, 

I am a new user for MCCDAQ USB-1608FS PLUS. Currently i am in middle of project which using a sensor, adc(MCCDAQ USB-1608FS PLUS) and also raspberry pi 4. I have installed uldaq library for calling mccdaq into my coding. I want to use a_in_scan in order to collect real time data with 100ks sampling rate.

Im having issue on this a_in_scan which give me result error displaying:

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Traceback (most recent call last):
    ai_device.a_in_scan(0, 0, AiInputMode.SINGLE_ENDED, Range.BIP10VOLTS, samples_per_channel, rate, ScanOption.DEFAULTIO, AInScanFlag.DEFAULT, buffer)
  File"", line 129, in a_in_scan
    raise ULException(err)
uldaq.ul_exception.ULException: ULError.NO_CONNECTION_ESTABLISHED: No connection established

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The mccdaq is connected well. Few coding without using a_in_scan can be run smoothly. But i need to use a_in_scan because i need the data to be collected within 100ks sampling rate. I attached my full coding. 

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import datetime
from uldaq import (get_daq_device_inventory, DaqDevice, InterfaceType, AiInputMode, Range, ScanOption, AInScanFlag, create_float_buffer)

# Configure DAQ device -----------------------------------------------------
devices = get_daq_device_inventory(InterfaceType.USB)
if len(devices) == 0:
    print('No USB-1608FS-Plus device found')
    exit(1)

device = devices[0]
daq_device = DaqDevice(device)
ai_device = daq_device.get_ai_device()
ai_info = ai_device.get_info()

# Configure analog input channel ------------------------------------------
channel = 0  

# Configure sampling -------------------------------------------------------
# scan_options = AInScanFlag.Default
rate = 5000 # Sampling rate in samples per second
num_channels=1
samples_per_channel = 100000  # Number of samples per channel to collect
buffer=create_float_buffer(num_channels,samples_per_channel)

# Start data acquisition ---------------------------------------------------
ai_device.a_in_scan(0, 0, AiInputMode.SINGLE_ENDED, Range.BIP10VOLTS, samples_per_channel, rate, ScanOption.DEFAULTIO, AInScanFlag.DEFAULT, buffer)

while True:
    current_time = datetime.datetime.now()
    # Read available data
    data = ai_device.a_in_scan_read(samples_per_channel)
    print('Time:', current_time, 'Voltage:', data)

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Hope you can help. Thank you!