increment a alphanumeric numeric value on button click

Question

How to increment a variable that is alpha numeric for every button click and display the incremented value for every increment.

 If i am having a variable named Order number that is intialised to 1 and it should be concatenated to ABC like ABC1 and it should be incremented by 1 for every button click the code in C# is as follows:

 

 

ViewState["count"] = Convert.ToInt32(ViewState["count"]) + 1;

label1.Text = ViewState["count"].ToString();

if (OrderID >= 10000000)

{

CompleteOrderId = string.Concat(Prefix, OrderID.ToString());

if(CompleteOrderId.Length<=11)

label2.Text = CompleteOrderId.ToString();

OrderID++;

if (label1.Text != null)

{

(CompleteOrderId + 1).ToString();

DisplayOrderID.Text = CompleteOrderId.ToString();

DisplayOrderID.Visible = true;

}

here it is displaying the count of button click but not incrementing the completeorder ID number . Kindly help me with this. Thanks in advance