Probably need to see all of your code in that macro rather than just one line.
However ... two probable causes:
#1 - The file is no longer where you remember it being and Excel can't find it.
#2 - Part of your code is missing.
Regarding #2 ... example code:
Code:
Sub ImportWorksheet()
' This macro will import a file into this workbook
Sheets("Sheet1").Select
PathName = Range("D3").Value '<--- could easily be the actual path instead of the path written to a cell
Filename = Range("D4").Value '<-- could be the actual filename instead
TabName = Range("D5").Value
ControlFile = ActiveWorkbook.Name
Workbooks.Open Filename:=PathName & Filename
ActiveSheet.Name = TabName
Sheets(TabName).Copy After:=Workbooks(ControlFile).Sheets(1)
Windows(Filename).Activate
ActiveWorkbook.Close SaveChanges:=False
Windows(ControlFile).Activate
End Sub
Note there is a reference made to Filename and Pathname so Excel knows
what is meant by Filename:=
PathName & Filename
Does you code provide the reference for
fileloc ?