Okay. I'm learning reporting services here. I've added a new empty report to my VB project. The datasource is setup. I have the dataset configured to use a stored procedure in sql. The procedure has one parameter (a guid). However, when I click the exclamation point to get copy of what is returned I am unable to specify a guid and receive an error! I've tried pasting a valid guid in there, but receive an error. I've even tried putting single and double quotes around it, no luck! I just receive an error that a string can't be converted into a guid. I believe that the report designer is trying to execute the query and is passing a string instead of the guid. Any ideas where to start here

Using a guid from the designer
SavageE
Use text as the type of the Data rather than 'stored procedure'. Add the text to run your sp i.e. exec SF1 @guid
Then when you execute the query and it asks you for the parameters, add the guid with curly brackets round it. I had the same problem and this worked for me.