I am using advanced filter and want to filter for a blank cell. I thought
that, to do this, you would use a "" but this does not appear to work. Is
there another way to filter for blank cells, or am I wrong?

Check http://groups.google.fi/groups?q=adv....com&rnum=3 1

In other words, the criteria should be =f3="", where f is the column
in which you test for blanks and the third row is the first which can
contain data, that is, not a header row. An example: the following
criteria range excludes rows where column F (header pet) begins with
dog or cat or is blank. No header label above the formula.

pet pet
<dog* <cat* =f3<""

regards
bb