Ebay csv listing upload error - VariationSpecificsSet container (Item.Variations.VariationSpecificsSet) is required to list a Multi-SKU item

I'm trying to upload a csv file on ebay fileexchange tool to bulk upload product listings but it shows an error message after uploading.

"Error - VariationSpecificsSet container (Item.Variations.VariationSpecificsSet) is required to list a Multi-SKU item."

Please can you help me to solve this issue?