Strumpy Shader Editor: Blending multiple textures?

SOLVED!
how? Change the subtraction to multiply. Otherwise you get negative values. lol.

I'm working on adding texture to my custom terrain, and I decided to try making a shader with SSE.

This image should explain what I'm trying to do (and perhaps what I'm doing wrong):



As you might be able to tell, I have 4 textures, two of which are textures I'd like to display (the sand and grass).
The two others describe what parts of the other textures will be displayed. I try to take the RGBA value from the sand texture and subtract it by the sandSplat textures alpha channel.

Thanks in advance.