It seems like the error message you are receiving is related to the field name in your October data source. The error message is indicating that the field name is not valid.
To resolve this issue, you can try the following steps:
- Check the field names in your October data source and make sure they are spelled correctly and do not contain any special characters or spaces.
- Ensure that the field names in your October data source match the field names in your previous data sources (August and September).
- If the field names in your October data source are different from the previous data sources, you can try renaming them to match the previous data sources.
- If none of the above steps work, you can try creating a new PivotTable using the October data source and see if the issue persists.