Error message during Databind in C#/Visual Studio 2008

I am trying to databind an integer from a text box and am getting the following error:

System.FormatException was unhandled
  Message="Input string was not in a correct format."
  Source="mscorlib"

I am successfully populating a text box with a number - say 21139.

This is the line of code I am getting the error on:

mortgee.MortId = int.Parse(this.txtNextMortId.Text.ToString());

Where mortgee is a business object i have created, and MortId is a public member that is an integer.

Any Ideas.. I hope I described this ok.

I try to bind to this value with the below code: