Tables :: MS Access Setting Relationship And Bound Column

I have three tables.

Table 1: Group

Field 1: Group Text field ( Primary key)
Field 2: Group Description Text field
Field 3: Uidgroup( Autonumber)

Table 2: Subgroup Text field

Field 1: Group ( I want to bound this column to Table 1's Group field that is column 1) I have set bound column property to 1 and column count 1 and the Subgroup table is showing group fields as input perfectly no issues in that )

Field 2: Subgroup, Text field( Primary Key )

Field 3: uidsubg( Autonumber)

Table 3: Email

Field 1: Group ( Bound to Table1's Group ; showing values in combo box, setted bound column property to 1 and showing group field perfectly, no issue in that )

Field 2: Subgroup (I want to bound Table2's subgroup field, which is column number 2, so I wrote 2 in bound column property and row source is table subgroup ; Here is some error comes up, values from subgroup field of subgroup table not being shown up in Email Table's subgroup field as combo box. )

Field 3: Email Text field

Field 4: uideml (Autonumber ) primary key

I want to prepare a Data entry form should have all these fields from all the tables. That should work in following way, first user selects Group then User selects Sub Group and write Email and save the record.

What relationship should I set, or shall I change the table structure.