Sorry for my English. I do some things as follows: 1. Create two render-target texture S(scene) and B(bump). 2. Render scene to S texture. 3. Render some objects(object's texture only has red and green) to B texture. 4. Use B to offset S's texcoord for producing distort effect. (I used ps 2.0) In shader,sample B is ok,But use B(texcoord) to sample S don't correct for some pixel. I change S to normal texture (I read data from image file.) do step 3~4 ,result is ok. Who can tell me,how to solve the problem. //DirectX 9.0c //Geforce 5200 Thanks.

Thx your reply!!

My Vs and PS codes as follws:
////////////////////
vs_2_0
dcl_position0 v0;
dcl_position1 v1;
mov oPos,v0;
mov oT0.xy,v1;
///////////////////
//c0 [scale_x,scale_y,0,0] => scale bump offset
ps_2_0;
dcl_2d s0; //Scene Texture(ocean box)
dcl_2d s1; //Bump Texture(four spheres)
dcl t0;
dcl t1;
texld r0,t0,s1;
mad r0.xy,r0,c0,t0;
texld r0,r0,s0;
mov oC0,r0;
///////////////////

if "S"(ocean box) and "B"(four spheres) are RenderTarget,result is as follows:
http://61.63.96.118/error.jpg

Then I changed "S" to normal texture(read data from image file),result is as follows:
http://61.63.96.118/ok.jpg

I don't use two rendertarget texture at the same time?