Project compilation

[Terry]

My application has references to many other assemblies which compile and run perfectly within the Visual Studio IDE. However, a line compiler which uses the Compile Class (and has worked well generally) is now unable to find a reference to an assembly (although reference to the same assembly within the Visual Studio compilation and build does not present an error). I have checked all references and don't see an obvious error. Indeed the fact that the application performs fine within Visual studio makes the problem even more intriguing. Can anyone suggest where I should start looking for the cause of the problem where the error message is specifically:

System.Exception: Compiler Errors :\r\nLine 0,0\t: could not find library 'myAssembly.dll'\n

Any help greatfully accepted.