dhtmlxValidation.trackInput is not a function

I write this code but don’t work. Why?

Grid code

grid.enableValidation(true,true);
grid.setColValidators("maxlength1,maxlength8,maxlength1");

Validator code

[code]
dhtmlxValidation.maxlength8 = function(data)
{
return maxlength(data,8);
}

dhtmlxValidation.maxlength1 = function(data)
{
return maxlength(data,1);
}

maxlength = function(value,length)
{
return (value.length() <= length);
}[/code]

I receive from firebug two different notification:

Please check if you have included dhtmlxgrid_validation.js file to your page

Thank you!