[Geotiff] _TIFFVGetField dying for some tags.

[Benjamin Scherrey]

I'm working on some GeoTIFF files and everything seems to be going fine 
but when I try to access some of the extended tags the library is 
trapping. Specifically all attempts to get to TIFFTAG_GEOTIEPOINTS and 
TIFFTAG_GEOPIXELSCALE via TIFFGetField die inside _TIFFVGetField around:

else     // Assume TIFF_VARIABLE
    *va_arg(ap, uint16*) = (uint16)tv->count;

I'm not able to figure out why its dying and would appreciate any ideas. 
Am I supposed to request these GeoTIFF extended tags differently or 
aren't they accessable via the TIFFGetField call?

  thanx & later,

     Ben Scherrey