I have seem some odd things when working directly between Excel and Access (sometimes they talk to each other and assume too much!).
Out of curiosity, does it happens if you export to Excel using the OutputTo action instead of the TransferSpreadsheet action, i.e.
Code:
DoCmd.OutputTo acTable, "BuyAKit", "MicrosoftExcelBiff8(*.xls)", efn, False, "", 0
Also, out of curiosity, what is the value of "efn"? I wonder if you might get odd results if you choose a file name that have an extension that is not a valid Excel extension.