How do you save Large Objects in Access2007?

Question

I am importing data (Pdf, Xls, Doc, Txt) into an Access 2007 Database....then I convert it to Base64 (called strData below). If the original was about 150K or less then I can save the converted file (about 250K characters) into a memo field. However, if the original is larger than that then the code gives me "run-time error '2498': An expression you entered is the wrong data type for one of the arguments".

Any suggestions how to save the larger files in Access 2007????

sSQL = "Insert Into tblAttachment(AttachmentDetail) Select '" & strData & "';" DoCmd.RunSQL sSQL