Fields in Tablebox must be visible as per Role Specified

Form 18 - G/l Account List
Some Fields (Debit Amount, Credit Amount....etc) we have to make Visible as Per the Role Assigned to Specific Users.
Below is the Code written on Form 18:

Form - OnOpenForm Trigger
MemberOf.RESET;
MemberOf.SETRANGE(MemberOf."User ID",USERID);
MemberOf.SETRANGE(MemberOf."Role ID",'COA');
IF MemberOf.FINDFIRST THEN
BEGIN
CurrForm."Debit Amount".VISIBLE(TRUE);
CurrForm."Credit Amount".VISIBLE(TRUE);
END ELSE BEGIN
CurrForm."Debit Amount".VISIBLE(FALSE);
CurrForm."Credit Amount".VISIBLE(FALSE);
END;



Now the problem is that the Users who do not have Role assigned to his ID can do Show Column and make the Field Visble.

Can Somebody help me that the Others user who do not have role assigned should not see the Fields.


Thanks in Advance.