Can't calculate area of Thiessen polygons, raw or dissolved.

Discussion created by tamsen_tremain on Dec 26, 2012
Latest reply on Dec 28, 2012 by tamsen_tremain

A few questions:

1) I have X,Y point data from which I've generated Thiessen polygons as one layer. I then clip this layer to another to get my final boundaries and dissolve by an attribute (habitat class). In the attribute table of each, I've added a new field and tried to run "field geometry" to get the total area of each polygon. The "area" selection in the dropdown box is "disabled". Does anyboyd know why I cannot generate the area of each Thiessen polygon?

2) The Thiessen polygon attribute table has lots of "Null" values entered in cells that previously held data. ????

3) In the final dissolved layer there are several wispy lines (incomplete polygons). Too many to delete manully via the Edit tool.

Answers in simple, advanced beginner's GIS language would be most appreciated.
Thank you.