Request.Querystring returning Object reference not set to an instance of an object

Hey guys -
I have been struggling with this one and I hope someone has an idea.  I have a series of values I pass/read from a querystring. I needed to add one more to my flow but now I'm hitting an 'Object reference not set to an instance of an object' error. The coding looks the same as the rest of my parameters... any ideas?
Here's my VB - the new field I'm trying to write out is "LengthOfTreatment"
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load CurrentDate.Text = Date.Now.ToString("D") LabelServiceSubtotal.Text = Request.QueryString("SubTotal").ToString() LabelDiscAmt.Text = Request.QueryString("DiscAmt").ToString() LabelDiscPctg.Text = Request.QueryString("DiscPctg").ToString() LabelEstimatedInsurance.Text = Request.QueryString("EstIns").ToString( ...