Where do you catch shellder in Pokemon platinum?

You can catch shellder in the museum at Oreburgh city,,, to catch it you must go through a secret passageway in the back and you ill find a secret garden with shellder's and eevee's.

It don't work wheres the secert passageway.!!!.!!!?!!!

There is no such thing. You get a shielder on route 205 with a super rod, and eevee are found in the Trophy Garden or in front of the mansion.