Line 6 has an error, am I not using DIM correctly?

Same mistake I often make. For SmileBasic, arrays use [square brackets] instead of (round brackets).

Okay.

Ohhh, have you been trying to port the raycaster I made in Petit Computer? I made a raycasting library for SmileBASIC that's a lot better, it comes in the RAYCAST.LIB file in public key QK4N3PZF.