Activate control in subform

[MCantu]

I would like I have a form and a subform.

I would like the control on the main form, when it's done running, to activate a command button in the subform.

Subform is 72sort subform
the command button is command4


I have tried so many things I don't remember what I have tried anymore.

Can someone please steer me in the right direction?
I know this is simple...isn't it?

 

[MCantu]

Btw

I already tried :
me.sortersubform.Form!command4

I get "Compile error, Expected ="

 

[MCantu]

Also Tried=- help!!!!

Call Forms("72sortersubform").Command4_Click
It says it can't find my form.

I double checked, the name of the subform.

Command4 is NOT private.