Export Date Range add-on not working

The export data range add-on of my A+ installation is no more working.

When I select a start date and an end date and press the export button I get a blank page with http 500 error.

It used to work correctly a couple of A+ versions ago.

Can you please check and help me solve the problem ?

I activated the support access if you need to check my site.

Thanks a lot

kind regards

Antonio