Data Shuttle Not Recognizing Smartsheet Source File

I have tried 100 times to link my source file (Smartsheet File) to another Target (Smartsheet File) and the source file will not map at all. I have data that is exported from SAP that I need to upload weekly, however, when I upload the data to smartsheet a new smartsheet is created. I can not link formulas every week. So I thought the data shuttle would be the answer. This is not working. I can't use data mesh because there may or may not be unique identifiers that can be synced as the SAP data may need to add data. Excel would be perfect in this case, why is smartsheet so difficult? Please help.