Don't quote me, but I think a Master/Child link on a form/subform will only take one column.
Double click the subform in design view and select the data tab, then select the Master and Child fields you want to use.
You alternative is to code this OR use a query with criteria that look to the controls on your main form.
So the query behind your subform with have this as criteria for txtExecID:
And the txtCode field in the query would have this criteria:
For both of these, they may be referencing columns in the text box or combo box you are using.
The thing is, doing it this way means that only records that satisfy both field values will be returned.
Do you have more info?