Error in SQL sintax

'you have an error in your SQL sintax. Check the manual that corresponds to your mysql server version for the right sintax to use near "at line '.

When eqsaldo=0 (zero) I receive this message.

procedure transac.movimento;
begin
tabelas.THist.Open;
tabelas.THist.Insert;
tabelas.THistsaldoqtd.Value := eqsaldo;
tabelas.Thist.Post;
tabelas.Thist.Close;
end;

"tabelas’ is Data Module and “Thist” is a Delphi object TTable.
When eqsaldo > 0 (zero) no problem: eqsaldo value is corretly inserted into table.
I use Wamp server with MySQL 5.5.8. and Delphi 7.

The table"s structure is:
CREATE TABLE IF NOT EXISTS histacoes (
id int(4) NOT NULL AUTO_INCREMENT,
titular varchar(8) NOT NULL,
ativo varchar(8) NOT NULL,
data date NOT NULL DEFAULT ‘0000-00-00’,
nota varchar(8) NOT NULL,
agente varchar(10) NOT NULL,
hist varchar(4) NOT NULL,
quant int(11) NOT NULL DEFAULT ‘0’,
cota decimal(10,2) NOT NULL DEFAULT ‘0.00’,
vrativo decimal(10,2) NOT NULL DEFAULT ‘0.00’,
corret float(10,2) NOT NULL DEFAULT ‘0.00’,
emol decimal(8,2) NOT NULL DEFAULT ‘0.00’,
vrliquidocompra float(10,2) NOT NULL,
saldocompras float(10,2) NOT NULL,
vrliquidovenda float(10,2) NOT NULL,
precomedio float(10,2) NOT NULL,
custodia decimal(8,2) NOT NULL DEFAULT ‘0.00’,
taxas decimal(4,2) NOT NULL DEFAULT ‘0.00’,
baseir decimal(10,2) NOT NULL DEFAULT ‘0.00’,
ir decimal(10,2) NOT NULL DEFAULT ‘0.00’,
saldoqtd int(11) NOT NULL,
PRIMARY KEY (id)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=15 ;

Please help me.
Tks