Change Spawner

I have warrior rank and it states that i can change the spawner type with "/spawner (name of mob)"

but when i do this it wont let me change it?

suggestions?

 

I think you have to place it down and be looking at it before you type the command to change it.

 

Yes, you have to place the spawner down and look at it then type, /spawner chicken or /spawner cow, pig, sheep. Those are for warrior rank <---