Problem trying to redraw a table

Graemef

I have a button associated with a dataTable which will allow the user to select all the rows on the table. I then redraw the table with a simple:
[code]...
oDataTable[t].fnDraw(false);
...[/code]

This all works until I add more tables to the page, for this example I have three tables. Then I get an error: "TypeError: oSettings is null". The error is in fnDraw() when it tries to get the oSettings object:
[code]var oSettings = _fnSettingsFromNode( this[DataTable.ext.iApiIndex] );[/code]
debugging gives me the following values:
[code]this : [table#inventory_list_1.dataTable]
DataTable.ext.iApiIndex : 2[/code]
this result is that this[DataTable.ext.iApiIndex] is undefined and so _fnSettingsFromNode returns null.

So my question, what am I doing wrong when calling fnDraw()? - I works with just one table but not with multiple tables.

Thanks,

Graeme