Need help with dependent parameters

Good Morning,

I have created a report with three different parameters and out of these 3 , one is a date parameter and the other two paramters are dependent on each other. I have a parameter called ZONE and in the drop down it has values 1,2,3,4 and the other parameter is CASEID (this is also a drop down). The way it is shwing results now is.In the ZONE parameter if i select value 1 then in the next parameter selection i should only see CASID's in the range 1000 to 1999.In the zone parameter if i select 2 then the correspong CASEID's (in this case 2000 to 2999) should be displayed in the second parameter drop down. But for some reason in my case , irrespective of the parameter i choose in ZONE all the available values are getting displayed in the second parameter. Can anyone please tell me or guide me in the right direction?

Thanks

SV