DAL ADD METHOD don´t show error

when use specific button to eg add a record via DAL with ADD method and random data generate duplicate key in a UNIQUE index in the mysql database does not include the record but also shows no error on page PHP
example:

$tblx_protheusmenu = $dal->Table("x_protheusmenu");

$tblx_protheusmenu->Value["XPRM_EMPRESA"] = $empresa; //$_SESSION["EMPRESA_COD"];

$tblx_protheusmenu->Value["XPRM_MENU"] = $matrizmenu[$i][1];

$tblx_protheusmenu->Value["XPRM_MODULO"] = substr(substr($matrizmenu[$i][1],-8),1,3);

$tblx_protheusmenu->Value["XPRM_TIPO"] = $matrizmenu[$i][0];

$tblx_protheusmenu->Value["XPRM_NIVEL"] = $matrizmenu[$i][2];

$tblx_protheusmenu->Add();