# Sprite rotation and question about sampler state

I'm not an expert in creating game engines, but I'm doing fine for now. Recently I reached a point that I couldn't solve any of my problems. I have two questions:

1. I'm using D3DXMatrixTransformation2D to produce the transformation matrix for my sprites, but I have a problem with rotation. Whenever I try to set a rotation for my sprite, it does turn when there is a fixed value of rotation. If I give 0.5f it won't rotate, but when I set 1, 2, 3, ... it'll work and that's not really cool. And, I searched a lot about pScalingRotation but it seems it's hasn't any influence. My rotation's value is fine, but the produced matrix doesn't act the way I expect it to.

2. I want to get a smooth edge for my sprites when they're rotating and I saw p_device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);. Where should I set the sampler state? After creating the device or after every update? And, what about texture filters? I use D3DXCreateTextureFromFileEx to load textures from file and it has Filter and MipFilter. Are these related to the sampler state?