Intellij downloads Gradle dependencies but cannot resolve symbols - intellij-idea

Question

When I try and use dependencies I have set out in my build.gradle Intellij cannot build the code and raises errors java: cannot find symbol. How can I get Intellij to recognise my dependencies?
PS: The lbrary is showing up in "External Libraries" and I am also having this issue with all my other dependencies.
In my build.gradle I have this:
...
dependencies {
...
compile 'com.squareup.okhttp:okhttp:2.1.0'
}
In my code I try and use this library:
import com.squareup.okhttp.OkHTTPClient;
...
OkHTTPClient client = new OkHTTPClient();
errors raised on both lines.
EDIT from comment: Command line build fails with the same errors, I guess I wrongly blamed Intellij. How can I tell why the dependencies are not being downloaded? They are sitting in my build.gradle in dependencies just as I showed. They are also present when running gradle dependencies under compile, default, runtime, testCompile and testRuntime, but not archives. Is that where the issue lies?
EDIT2: Ouput of gradle dependencies:
:dependencies
------------------------------------------------------------
Root project
------------------------------------------------------------
archives - Configuration for archive artifacts.
No dependencies
compile - Classpath for compiling the main sources.
+--- com.google.code.gson:gson:2.3.1
\--- com.squareup.okhttp:okhttp:2.1.0
\--- com.squareup.okio:okio:1.0.1
default - Configuration for default artifacts.
+--- com.google.code.gson:gson:2.3.1
\--- com.squareup.okhttp:okhttp:2.1.0
\--- com.squareup.okio:okio:1.0.1
runtime - Classpath for running the compiled main classes.
+--- com.google.code.gson:gson:2.3.1
\--- com.squareup.okhttp:okhttp:2.1.0
\--- com.squareup.okio:okio:1.0.1
testCompile - Classpath for compiling the test sources.
+--- com.google.code.gson:gson:2.3.1
+--- com.squareup.okhttp:okhttp:2.1.0
| \--- com.squareup.okio:okio:1.0.1
\--- junit:junit:4.11
\--- org.hamcrest:hamcrest-core:1.3
testRuntime - Classpath for running the compiled test classes.
+--- com.google.code.gson:gson:2.3.1
+--- com.squareup.okhttp:okhttp:2.1.0
| \--- com.squareup.okio:okio:1.0.1
\--- junit:junit:4.11
\--- org.hamcrest:hamcrest-core:1.3
BUILD SUCCESSFUL
Total time: 1.82 secs