@Raja.G ,
If the Json was already converted to Dictionary, then the expression you have used should get the value i.e the regex expression.
io_config("str_name").ToString
Maybe you want to loop all the values in the Json and use the Regex Expression present in each of them in Matches Activity ? If so, Try to use For Each Loop Activity and Pass the Dictionary as the Value to loop. Then we could access the Key and Value using .Key and .Value Properties.
