Parameter map help required in cognos relational model

[xyz]

Hi Gurus,

We have requirement where we have to create a parameter map with a prompt macro which should be optional. We are using cognos 10.2 with relational model. We are creating a parameter map in Report studio. We used the below expression, when we use the below expression individually then it is executing fine.  But which will make it mandatory. We want the prompt macro to be optional, below expression works fine when no input is passed to the parameter map but when we pass the parameter we are getting a trace back error.

(#$SearchParameterMap{prompt('Search_Name','token',"'NoValue'")}# )
or
('NoValue'=#$SearchParameterMap{prompt('Search_Name','token',"'NoValue'")}# )

Can some one please give me suggestions?

Thanks & Regards,
XYZ