how to make Multiple parameters to sql query string seperated by ,(comma) ..

Hi,

I would like to konw how I can make multiple parameters to sql query string seperated by ,(comma)  ..

For example, this parameters can be printed like 'abc,dde,ggf,eeg' ,once I use  "join(Parameters!rpCode.Value,",")" with report builder , 

By the way, when I test this multiple parameters by Query Designer of report builder there was no problem,.(using Define query parameters, I put abc,dde,ggf,eeg)

however, when I run this report , it won't be executing ,  with (rsErrorExecutingCommand)

Plz, help me....