c# - CSharp ado.net Error converting data type nvarchar to numeric -

suppose have table 3 column

   id       int    name     nvarchar(63)    age      int 

and have procedure search row match keyword input.

create procedure usp_search   @keyword nvarchar(63) begin     sekect * tblpersonal                                  @keyword null                 or @keyword  = age                 or name n'%'+@keyword+'%'   end 

when tested sql management tool work fine

declare @return_value int  exec    @return_value = [dbo].[usp_search]         @keyword = null 

but when execute in ado.net , pass dbnull.value sqlparameter had error

"error converting data type nvarchar numeric"

anyone can tell me different ado.net , environment of sql management tool

the problem on line:

or @keyword  = age 

the column age integer , @keyword string. prevent getting error, convert data type of age string,

or @keyword  = cast(age nvarchar(5))