adding validation controls

[wellery]

I'm trying to work out how to do this. So far I keep getting errors
"Unable to find control ID..."

What I've got is a datefield control which draws a calendar popup and a
text field. I draw two of these date fields on a page by adding them to
the controls collection. The dates work fine however I want to add
validation to them to ensure the first date is less than the second
date but this isn't working. So far I'm doing this:

//creat objects
CompareValidato r objCompareDateV al = new CompareValidato r();
PUDateField objStartDateFie ld = new PUDateField("St artDate);
PUDateField objEndDateField = new PUDateField("En dDate);

//setup compare validator
objCompareDateV al.Operator = ValidationCompa reOperator.Less ThanEqual;
objCompareDateV al.ControlToVal idate = objStartDateFie ld.ID;
objCompareDateV al.ControlToCom pare = objEndDateField .ID;

//add the controls
this.Controls.A dd(objStartDate Field);
this.Controls.A dd(objEndDateFi eld);
this.Controls.A dd(objCompareDa teVal);

In the date field I also used:

[ValidationPrope rtyAttribute("V alue")]

public string Value
{
get
{
return this._objTextBo x.Value;
}
set
{
_objTextBox.Val ue = value;
}
}

I'm not sure If I'm doing this the right way. Can someone please point
me in the right direction on how I should accomplish what I'm trying to
do? Thanks