Error creating dBase index

Hi!

I'm creating a table on the fly using ttable.createtable and then creating
index files for some of the fields.

I'm using

var
 newtable: ttable;

iname:='myIndex';
field1= the name of one field...
newtable.addindex(iName,field1,[ixDescending]);

Resulting in a EdbEngineError exception with message
"Invalid index descriptor. Table does not exist".

I also tried
newtable.indexdefs.add(iName,field1,[ixDescending]);
with the same result.

Any ideas of what I'm doing terribly wrong?

TIA,

Javier Espa?ol