Detail depend on Master

Hello gurus

How to make lookup statement on detail form depend on some value on master form.
I want my lookup value on detail form only show when [SomeId] = [SomeId] on master form
How to make it
thx b 4

When creating the link from the master form to the detail just select the fields you want to use as the link.

More detailed response:

On your Master Form select the New Detail from the Master/Detail Form option in the left tree menu.
Give the form a Name and Label.
Click Create
Select the Detail form
Click Next
Now you can select the key field(s) that will link the two forms together such as SomeId from the drop down.
Click Save

Hope this helps.