Queries :: Textbox On Subform As Query Criteria

I'm trying to build a query to use as a filter in the DoCmd.OpenForm function.

I have done this several times before, referencing values from forms e.g.

Point To
Field: LeadID
Table: Lead
Criteria: [Forms]![GridDisplay1]![LeadID]

This filter is used in the procedure:

Code : DoCmd.OpenForm "LeadDetails", acNormal, Point_To", , , acDialog, """"

And it works great, I click a button next to the record I want to select (records displayed on continuous form) and it opens the Lead Details form on that particular record.

However now I am trying to accomplish the same thing, except instead of a continuous form I need to draw from a continuous sub-form. The form "BrokerMgmt" contains a sub-form named "BrokerSearch." The RecordSource for the sub-form is set once the user enters data into a few textboxes on the main form and clicks the search button:

Code:
Private Sub brkSearch_Click()
Dim argCount As Integer
On Error GoTo Err_Handler
If IsNull(brkFirstName.Value) And IsNull(brkLastName.Value) And IsNull(brkCompany.Value) Then
MsgBox "You Need To Select Some Values", vbCritical, "Lead Tracking"

[Code] ....

The sub-form then displays basic info such as Name, Company, State, and the "BrokerID" which is the primary key of the "Broker" table. This "BrokerID" is displayed in "Textbox 20" so I set a button next to each result to on_click perform the procedure:

Code:
DoCmd.OpenForm "BrokerDetails", acNormal, "Point_To_Broker2", , , acDialog, """"
"Point_To_Broker2" is set up in the same style as "Point_To":
Field: BrokerID
Table: Broker
Criteria: [Forms]![BrokerSearch]![Text20]

However instead of the BrokerDetails form opening to the appropriate record I get a msg box asking for a parameter. Why is this? Even if I enter the correct BrokerID as the parameter it still gives me an error saying you can't go to the specified record.