When a VLOOKUP returns #N/A!, that means that it did not find any match in your table. When it returns 0, that means it found a match, but the corresponding value returned is either blank or actually has a value of 0.
To illustrate, lets take the following table for example:
Excel 2007<TABLE style="BORDER-BOTTOM: #a6aab6 1px solid; BORDER-LEFT: #a6aab6 1px solid; BACKGROUND-COLOR: #ffffff; BORDER-COLLAPSE: collapse; BORDER-TOP: #a6aab6 1px solid; BORDER-RIGHT: #a6aab6 1px solid" rules=all cellPadding=2><COLGROUP><COL style="BACKGROUND-COLOR: #e0e0f0" width=25><COL><COL></COLGROUP><THEAD><TR style="TEXT-ALIGN: center; BACKGROUND-COLOR: #e0e0f0; COLOR: #161120"><TH></TH><TH>A</TH><TH>B</TH></TR></THEAD><TBODY><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">1</TD><TD>Joe</TD><TD style="TEXT-ALIGN: right">1</TD></TR><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">2</TD><TD>Bob</TD><TD style="TEXT-ALIGN: right">2</TD></TR><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">3</TD><TD>Allison</TD><TD style="TEXT-ALIGN: right">3</TD></TR><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">4</TD><TD>Jane</TD><TD style="TEXT-ALIGN: right">4</TD></TR><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">5</TD><TD>Zane</TD><TD style="TEXT-ALIGN: right"></TD></TR><TR><TD style="TEXT-ALIGN: center; COLOR: #161120">6</TD><TD>Matthias</TD><TD style="TEXT-ALIGN: right">9</TD></TR></TBODY></TABLE><TABLE style="BORDER-BOTTOM: #a6aab6 1px solid; BORDER-LEFT: #a6aab6 1px solid; BACKGROUND-COLOR: #ffffff; BORDER-COLLAPSE: collapse; BORDER-TOP: #a6aab6 1px solid; BORDER-RIGHT: #a6aab6 1px solid" rules=all cellPadding=2><THEAD><TR style="TEXT-ALIGN: center; BACKGROUND-COLOR: #e0e0f0; COLOR: #161120"><TH>
Sheet1</TH></TR></TD></THEAD><TBODY></TBODY></TABLE>
If we look up Joe, Bob, Allioson, Jane, or Matthias, it will return their corresponding value. If we look up Zane, it will return 0. If we look up Robert, it will return #N/A!, as he is not on the table.
