Yes No or Both parameter

SSAS and SSRS
1

Hi,
Fro each record in a table, that I am querying, I have a field that has that identifies the account a major acct or not. So the field has in it either Mgact or Non_Mgtact,
I want in the report to have a parameter that is labeled major account, and in it has Yes, No, or Both.
If they chose Yes they get only Major accounts, if No they get non major accounts, and if both then they get both of them.
I have been trying a number of things and cannot get this.
Any help I would really appreciate it.
Thank you

2 
WHERE
(
       (@UserChoice = 1 AND AccountType = 'Mgact')
    OR (@UserChoice = 2 AND AccountType = 'Non_Mgtact')
    OR (@UserChoice = 3 AND AccountType IN ('Mgact', 'Non_Mgtact'))
)
3

Thank you that works