ASP.NET do not show eval in page - ASPxGridView - asp.net

Question

I have hopefully a simple question. I have a ASPxGridView that I need to pull data from and pass it to a function. A simple way I figured to do this is to use a session variable.
But when I do the Eval binding it shows the characters on screen (as well as putting them into the variable). How do I remove the characters from the screen? Or maybe there is a easier way to do this.
Code is here (real meat is 4th line down):
<dx:GridViewDataButtonEditColumn Caption="" Name="Schedule"
VisibleIndex="11">
<DataItemTemplate>
<%# Session["PatientID"] = Eval("PatientID")%>
<dx:ASPxButton ID="ASPxButton1" runat="server" Text="Schedule" OnClick="Button_Click" >
</dx:ASPxButton>
</DataItemTemplate>
</dx:GridViewDataButtonEditColumn>

Answer 1

Try this
<dx:GridViewDataButtonEditColumn Caption="" Name="Schedule" VisibleIndex="11">
<DataItemTemplate>
<dx:ASPxButton ID="ASPxButton1"
runat="server" Text="Schedule"
OnClick="Button_Click"
CommandName='SomeCoolCommandName'
CommandArgument='<%#Eval("PatientID")'>
</dx:ASPxButton>
</DataItemTemplate>
</dx:GridViewDataButtonEditColumn>
On it rowcommand or Itemcommand event check for command and do something..
protected YourGrid_ItemCommand(sender, e)
{
if(e.CommandName.Equals("SomeCoolCommandName"))
{
var id = Convert.ToInt32(e.CommandArgument); // Give you your Patient ID
// do whatever you want to do with your ID
}
}

Answer 2

Try to put a hidden field and bind its value like following
<asp:HiddenField ID="hdnPatientID" runat="server" Value='<%# Eval("PatientID")%>' />

Answer 3

I am adding the functional code here. Thanks all! Using command worked great.
protected void Button_Click(object sender, CommandEventArgs e)
{
string patID = e.CommandArgument.ToString();
Response.Redirect("schedule.aspx?PatientID=" + patID);
}
<dx:GridViewDataButtonEditColumn Caption="" Name="Schedule"
VisibleIndex="11">
<DataItemTemplate>
<dx:ASPxButton ID="ASPxButton1" runat="server" Text="Schedule"
CommandName = "PatientID" CommandArgument = '<%# Eval("PatientID")%>' OnCommand="Button_Click" >
</dx:ASPxButton>
</DataItemTemplate>
</dx:GridViewDataButtonEditColumn>