need help,how to fix this error

i create a form with table box and subform, table box and subform table source table is same,but only table view is diffrent.

table FIELD is like this:
1.code
2.code2
3.desc
4.count

example rec is like this:
code code2 desc count
C1 '' A 4
C1 CA1 A1 3
C1 CA2 A2 1
C2 '' B 2
C2 CB1 B1 2

table box only show rec with code2=''. when currrec in the table box is C1 subform only view CA1,CA2 and so on.

in this form i create textbox with option.
when i change the option, i delete all the rec and insert new rec.
the subform view the last rec that i before delete. then when i go to next rec it show this message:
cannot modify in this form.
after i ok then message .sub form view back to normal.
sorry, if my explain is confusing :oops: .