"Ambigious Match Found" - Works fine in develoment environment

A few days ago I ran into this problem while i was working for a project.Everything was working well in development environment.But when this was deployed in the production server things were not going as expected. After consulting with sohan and with the help of asp.net forum we figured out that my aspx page contained TextBox control "Email" and string variable email in the codebehind file

private string email;

and these two variables were raising ambiguity in the production environment though the two variables were of different types and of different casing.

After changing name of one variable the page was not raising any exception in the production environment.