code looks wrong and i think you put the file in wrong directory... Below is example code I use. Also be sure to save the sprite file to moddirectory/models/sprites.
Code:
// PRECACHE our sprites
PRECACHE_SPRITE(sprites/stflogo.spr)
// LOGO SPRITE BLUE BASE
{
netname/logo
classname/env_sprite
frame/1
framerate/10
rendermode/5
renderamt/255
scale/1.0
spawnflags/1 // SF_SPRITE_STARTON
model/sprites/stflogo.spr
origin/0 -862 -226
angles/180 90 180
}