Object Must Implement IConvertible

[Kat]

I have a gridview that queries a stored procedure to select id, firstname,
lastname from clients. Then I have a detailsview that queries the client
details linked to the id from the client gridview. If I put the select
statement for the client details directly into the datasource, it works
fine, but as soon as I put the select statement -- the exact same
statement -- into a stored proceudre, I get the above error. What does that
mean and how can I fix this? Thank you very much for your help.

 

[Teemu Keiski]

What's the object you are passing as data source or to the query? Usually
this occurs when object cannot be converted to a specific type.