Could younhelp on this scenario

Here am getting alert msg but g_form msg not triggering 

if (!/^[a-z]+$/.test(newValue))
///^[0-9*#+]+$/

{
alert(" name should be lower case ");
g_form.showErrorBox('u_name', 'name should be lower case',false);
g_form.showFieldMsg('u_name', 'name should be lower case','info',false);
g_form.clearValue('u_name');
}