You are not using GLSL 1.20. I know this because all of your calls end in ARB, which means you are using the ARB_shader_objects extension, which doesn't allow GLSL 1.20. Or if it does, it only works by accident. Don't use GLSL as an extension; use it as a core feature (no ARB suffix).
@Nicol Bolas: where have you found that ARB_shader_objects doesn't allow GLSL 1.20? The specification states only that it is written against GLSL 1.10, but it doesn't say when it is applicable!
Small changes to the APIs for managing shader and program objects were made in the process of promoting the shader extensions to the OpenGL 2.0 core. These changes do not affect the functionality of the shader APIs, but include use of the existing uint core GL type rather than the new handleARB type introduced by the extensions, and changes in some function names, for example mapping the extension function CreateShaderObjectARB into the core function CreateShader.