The issue happens because pzParseExcelFile expects the attachment content to be passed correctly as a byte stream, and changing the Java step directly is breaking the activity context. Keep the standard attachment handling as it is and make sure the Excel file is first loaded into the correct clipboard page or parameter that the activity uses before calling pzParseExcelFile. The USING_PAGE_ERR means the Java step is trying to use a page that is not available in that activity step. So the fix is to restore the original logic, pass the attachment through the expected parameter or page, and avoid editing the internal Java step in the rule. Once the file is available on the proper page, pzParseExcelFile will be able to read it without the pzUnrecognizedFile error.
This is because system is not able to find the file. First store the file in service export directory, then use pxParseExcelFile activity to parse the file.
In this post you will see the file being pushed to service export directory using pxCreateFile and then parsed.