problem with quadtreePrimitive branch

Hello,I download the quadtreePrimitive branch, but it has errors when I run it.

The erros is as follows:

An error occurred while rendering. Rendering has stopped.
This may indicate an incompatibility with your hardware or web browser, or it may indicate a bug in the application. Visit http://get.webgl.org
to verify that your web browser and hardware support WebGL. Consider trying a different web browser or updating your video drivers. Detailed error information is below:
RuntimeError: Fragment shader failed to compile. Compile log: ERROR: 0:237: ‘sampleAndBlend’ : no matching overloaded function found ERROR: 0:237: ‘assign’ : cannot convert from ‘const mediump float’ to ‘4-component vector of float’
Error
at new RuntimeError (http://localhost:8000/Cesium-quadtreePrimitive/Source/Core/RuntimeError.js:42:19 )
at createAndLinkProgram (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/ShaderProgram.js:675:23 )
at initialize (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/ShaderProgram.js:861:23 )
at ShaderProgram._bind (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/ShaderProgram.js:878:9 )
at beginDraw (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/Context.js:1784:12 )
at Context.draw (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/Context.js:1851:9 )
at DrawCommand.execute (http://localhost:8000/Cesium-quadtreePrimitive/Source/Renderer/DrawCommand.js:185:17 )
at executeCommand (http://localhost:8000/Cesium-quadtreePrimitive/Source/Scene/Scene.js:988:21 )
at executeCommands (http://localhost:8000/Cesium-quadtreePrimitive/Source/Scene/Scene.js:1217:17 )
at render (http://localhost:8000/Cesium-quadtreePrimitive/Source/Scene/Scene.js:1315:9 )
at Scene.render (http://localhost:8000/Cesium-quadtreePrimitive/Source/Scene/Scene.js:1350:13)

Can you help me with this problem?