Hi Panhu,
With Measurement & Automation Explorer 4.1 and NI-DAQmx 8.3.0f0, I was able to export my hardware devices from Devices and Interfaces and my NI-DAQmx Tasks from Data Neighborhood. Not sure why you would not be able to export your task information, but
this KB details how to export and import information to and from MAX. Please take a look and follow the steps for exporting your information. In the second step of the wizard, you should be able to expand your NI-DAQmx Tasks folder and select which tasks you'd like to export. If that folder does not exist, you might not have any tasks that are currently saved.
Hope that helps...let me know if you have any additional questions...
Regards,
Nicholas B
National Instruments