Texture issue with invisible slime:

In a command block i put in:

/summon Slime ~ ~ ~ {Riding:{id:MinecartRideable},ActiveEffe­cts:[{Id:14,Amplifier:0,Duration:32000,
Ambient:1}],Invulnerable:1,Size:2,Custom­Name:"forcefield"}

What I expected was a invisible slime in a minecart, which the minecart would be in the ground but the slime on and above ground level.

What i got was a slime with a texture of items from the game, not invisible.

1.place command block 1 block down from ground
2. type in the command block:

/summon Slime ~ ~ ~ {Riding:{id:MinecartRideable},ActiveEffe­cts:[{Id:14,Amplifier:0,Duration:32000,
Ambient:1}],Invulnerable:1,Size:2,Custom­Name:"forcefield"}

3. hit ok
4. place button on side of command block
5. place dirt block on top of command block
6. press button
7. object is spawned with wrong texture