HLSL image Shader Ps_2_0 Run no problem, ps_3_0 run a problem

a pixel shader was used in the recent development, I wrote a text data with D3dxcompileshaderfromfile to compile it, when I set to ps_2_0 a cut normally.

because the program needs to write more branch statements, and ps_2_0 the number of instructions such as limited, so I want to change to ps_3_0 version compile, compile normal "I tested the hardware, it is to support Ps_3_0 ".

Runtime discovery: The PS_2_0 image is displayed correctly; When using PS_3_0, the image is displayed incorrectly as a background image of the same color.

The way to resolve the problem: ps_3_0 needing a vertex shader . That is, when the PS_3_0 version is used, the support of the vertex shader is required to add a vertex coloring

Device after, run normally!

HLSL image Shader Ps_2_0 Run no problem, ps_3_0 run a problem