help me with mdi

hi guys, started recently with visual basic.net. And i'm enjoying it. But i have a problem with mdi. I cant seem to set them up.

i have set the ismdicontainer property parent form to true.
And my code looks like this:

Dim form3 As New Form3
form3.mdiparent = me
form3.show

But it doesn't seem to work..

Can anybody help me? What am i doing wrong?
Did I put this code in the wrong form?

hmmm...is it typo error?

dim form3 as new form3
form3.mdiparent = me
form3.show()

should be:
dim frm as new form3
frm.mdiparent = me
frm.show()

this should work, form3 is a new class, so u need to dim {variable} as new {class}...