CONCATENATION

Hi Friends!

I am using the below expression to concatenate the columns its working fine. But the problem is when the column is null I am getting the ','  operator  before the fields which I don't require. How to solve this problem? Please help me.

Fields!ADR_LINE_1_TX.Value&" , " &Fields!CITY_NA.Value &" , "&RTRIM(Fields!STATE.Value) &" , " &Fields!ZIP_CODE_AD.Value

Thanks

sush