Crystal Reports Multiple commands in crystal reports

Message

   I have 2 commands and 4 parameters. 
In the search screen i am looking for a drop down option like below

Report Type Product
Product Family

If the first is selected (ie product) i want the parameters to work on 1st command 
if the second is selected (ie product family) i want the parameters to work on 2nd command 

For which i have the below, BUT IT DOES NOT SEEM TO WORK.
If {parameter}=" Report Type Product" then Command1.field= {parameter} else
if {parameter}= " Product Family" then Command2.fiedl= {parameter}

Below is exactly what i have, the results returing is not correct. Looks like its doing a join or something

if {?ReportType} = 'Event' Then
(
(if {?LikeParameter} = 'Like' then 
(not HasValue({?EventName})) OR ({Command.EVENT_NAME} startswith {?EventName}) 
else
(not HasValue({?EventName})) OR not ({Command.EVENT_NAME} startswith {?EventName}) )
)
else if {?ReportType} = 'Event Country' Then
(
(if {?LikeParameter} = 'Like' then 
(not HasValue({?EventName})) OR ({Command_1.EVENT_NAME} startswith {?EventName}) 
else
(not HasValue({?EventName})) OR not ({Command_1.EVENT_NAME} startswith {?EventName}) )
)