I have checked the official website, but it doesn't specify the supported operating systems. If you have a version prior to 4.28.0 then I recommend you upgrade it to the latest version using the direct download URL posted below. Additionally, after upgrade, right click the executable file and go to Properties > Compatibility. Form the drop down menu, pick Windows 7 and tick the Run as Administrator option. Launch the software and repeat the same procedure. If if still gives you errors, them I recommend contacting the official developers of the application using the following contact method:
[email protected]
[email protected]
Download URL: https://www.invoiceexpert.com/InvoiceExpert-4.28.0-Setup.exe