compile error help

Our .NET programmer left a week ago and I am trying to make some changes to my menu_sup.aspx page using MS Visual Studio 2005. I get a compile error and I know that our programmer did some kind of build or compile when he made changes, but I do not know how to do this.

I tried building the project under the build tab but I am still getting the compile error. I do mostly html programing and know how to copy and paste asp changes and such to achieve what I want but this it totally new environment for me. I am learning by virtue of "baptism by fire" and would appreaciate a helping hand.

Here is a little more information on the error, I think the build is working ok I am just getting this error.

Code:

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Server Error in '/' Application.
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Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0165: Use of unassigned local variable 'isOff'

Source Error:

 

Line 78: 
Line 79:  image2on = new Image();
Line 80:  image2on.src = "/images/menu/<%=isOff%>";
Line 81:
Line 82:  image3on = new Image();
 

Source File: e:\clients\dimitroff\includes\menu_sub.ascx    Line: 80

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I figured out what was wrong. I had not declared my variable in the "else" section of my 'if' statement.

Thanks to those who considered helping.:)