Crystal Reports Group selection via Parameter

Message

   Hello,

Quick question. Im struggling here.

I have a simple report to show the yearly quarters sales by CUSTOMER.

amongst our customers, we have different BRAND DEALERS for different brands.

These dealers are identified in our database by a boolean field.

there are only 5 different types of brand dealers giving me 5 boolean fields.

{KUcheck}
{FAcheck}
{GEcheck}
{TOcheck}
{GTcheck}

I have these parameters in my report;

PERIOD

YEAR

BRAND

What I want to do is, if the brand parameter selected by the user, is say "KU" , then I want to have my customers group only show customers who have {KUcheck}=TRUE, 

and so on for the other 5 brands.

I have tried to enter this formula into the Select Expert under the GROUP selection part:

IF {?brand}="KU" THEN {Table.KUcheck}=TRUE ELSE

IF {?brand}="FA" THEN  {Table.FAcheck}=TRUE ELSE

IF {?brand}="GE" THEN {Table.GEcheck}=TRUE ELSE

IF {?brand}="GT" THEN {Table.GTcheck}=TRUE ELSE

IF {?brand}="TO" THEN {Table.TOcheck}=TRUE

But this is not working. It is returning ALL customers.

Can anyone advise please?

Thanks in Advance,

mike.