TypeError when trying to set sprite alpha

Hello!

I'm currently trying to set the alpha for a sprite through a tap. But I get an error in my script.

This is my script:

// Properties:

//@input Component.SpriteVisual ugsprite

// Sets the alpha of the sprite visual to 0.5

script.ugsprite.getMaterial(0).getPass(0).baseColor = new vec4(1, 1, 1, 0.5);

I have named my sprite "ugsprite" in under the Objects section, but the error I get when clicking is this: 

TypeError: cannot read property 'getMaterial' of undefined
at [anon] (Script:4) preventsyield

Could someone please help me find the cause to this? :)