SQL Stored Procedure parameter - Type Mismatch

Hi,

So I appreciate you create a parameter within a stored procedure and you then use that parameter within an SSRS report to filter your data. Am I correct in thinking that when you declare that parameter you match it to the data value type within the SQL Database? As I must be doing something wrong - I have done this and I get rsReportParameterTypeMismatch

In the table the data type is char(10) not null

so I have declared that within the stored procedure

CreatePROCEDURE[dbo].[DB_ADVICE](@BatchValuechar(10))ASSELECT.......Where....like@BatchValue

But it errors with

The value provided for the report parameter 'BatchValue' is not valid for its type. (rsReportParameterTypeMismatch) 

Any ideas? Thanks