Timeout with REQUIRES

[Abe Gillespie]

I have two layers that look like this:

  LAYER
   NAME "Flood Zone"
   STATUS ON
   DATA "flood_zo"
   TYPE polygon
   MAXSCALE 300000
   UNITS FEET
   CLASS
    COLOR 68 126 171
    OUTLINECOLOR 11 57 92
   END
   GROUP "Layers"
  END

  LAYER
   NAME "Flood Elevation"
   STATUS ON
   DATA "flood_el"
   TYPE line
   UNITS FEET
   MAXSCALE 20000
   CLASS
    COLOR 68 155 255
    TEXT ([ELEVATION]')
    LABEL
     TYPE TRUETYPE
     FONT arial
     SIZE 8
     POSITION cc
     COLOR 0 0 0
     ANGLE auto
     MINFEATURESIZE 1
    END
   END
   REQUIRES "([Flood Zone] = 1)"
  END

Notice the "REQUIRES" tag.  These two layers cause no problems.
However, I also have these two layers further in the map file:

  LAYER
   NAME "Buildings"
   STATUS ON
   DATA "bldg1"
   TYPE polygon
   MAXSCALE 15000
   UNITS FEET
   LABELITEM "ADDRESS"
   LABELCACHE on
   LABELMAXSCALE 6000
   CLASS
    COLOR 220 149 146
    OUTLINECOLOR 190 95 96
    LABEL
     MINFEATURESIZE 12
     TYPE truetype
     FONT arial
     ANTIALIAS true
     ANGLE auto
     POSITION cc
     COLOR 0 0 0
        OUTLINECOLOR 255 255 255
     BUFFER 3
     SIZE 8
    END
   END
   TOLERANCE 3
   TEMPLATE "x"
   METADATA
    search_field "FULLADDR"
    search_fields "FULLADDR"
    search_aliases "Address"
   END
   GROUP "Layers"
  END

  LAYER
   NAME "Buildings 0"
   STATUS ON
   DATA "bldg0"
   TYPE polygon
   MAXSCALE 15000
   UNITS FEET
   CLASS
    COLOR 168 168 168
    OUTLINECOLOR 97 97 97
   END
   REQUIRES "([Buildings] = 1)"
  END

With the "Buildings 0" layer, if I include the "REQUIRES" tag MapServer
will timeout.  If I remove the "REQUIRES" tag everything runs smoothly.
  I'm using PHP Mapscript 4.4.1.  Before I upgraded (I think it was
Mapscript 4.0) this worked fine.  So something has changed between then
and now with the "REQUIRES" algorithm.

Any ideas?

Thanks.
-Abe