Error in SSRS Expressions

I am having an expression which is supposed to give me the values selected in a multivalued input parameter. I have tried following options however everytime it gives me error. Could someone let me know what might be the issue here.

1. Expression: =Parameters!i_Category.Label

Output: The Value expression used in textbox ‘textbox47’ returned a data type that is not valid.

2. Expression: =Parameters!i_Category.Label.ToString()

Output: System.Object[]

3. Expression: =CStr(Parameters!i_Category.Label)

Output: Error: Conversion from type 'String()' to type 'String' is not valid.

Take a look at this link for more information about parameters and working with multi-valued parameters.

http://msdn2.microsoft.com/en-us/library/aa337292.aspx|||Thanks Ian. It helped me a lot.