Welcome to the Community, @sfanzoi.

Let me share information regarding your problem with importing your data in QuickBooks Desktop (QBDT).

If you have added INVITEM on the !TRNS row as a field that would cause the message above. INVITEM should be included on the !SPL row.

I would also like to ask if you have turned on your tax option, and it happened that it won’t charge taxes, I recommend entering a zero in the sales tax column for the transactions without tax.

I also recommend Verify and Rebuild data utilities. They automatically fix company file data issues, but remember to back up your file before running the rebuild tool. You can also update your QuickBooks to resolve any missing program files that could have caused this error.

In addition, I'll leave you these articles that outline the details about IIF and its limitations when importing and exporting IIF files:

• Import IIF Files
• IIF Overview: import kit, sample files, and headers (I suggest using a dummy company file when trying the samples.)

Let me know if you have other inquiries when importing your files in QuickBooks Desktop. I’ll be right here to assist you. Have a great day ahead!