Solution
This could be because the dataplugin for this type of file might not be installed. You can check this following the next steps:
1. Ensure that the DIAdem software is properly activated.
2. In DIAdem, go to Settings>>Extentions>>Dataplugins.

Ensure that the Plugin is installed.

3. If the Plugin is not available, install it separately from the ni.com, for instance :