Problem With Insert Using SQLDataSource

I have a table with 2 columns - "memberid" is a guid and "Interest" is a string. In an aspx page I want to read in all values of "Interest" for a given "memberid" and display approprite checkboxes as checked. The user can then change which boxes are checked and I want to record the new list of selected items in the table. I created a SQLDataSource (see below) but when I run it, I get this error:

==========  Error  ===========

Disallowed implicit conversion from data type sql_variant to data type uniqueidentifier, table 'DB_136571.dbo.gs_MemberInterests', column 'memberid'. Use the CONVERT function to run this query.

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The only use of this SQLDataSource is to delete all entries for a given user and then insert an entry for each checked checkbox. The code to set the session variables is as follows:

========  Code  ============

Dim guidMemberid As Guid = CType(user.ProviderUserKey, Guid)

Session("currmember") = guidMemberid

.....

Session("currinterest") = CType(item.FindControl("CheckBox1"), CheckBox).Text

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Any ideas of what I am doing wrong here?

 

========= SQLDataSource ==========

<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:GoodSamSiteDB %>"

DeleteCommand="DELETE FROM [gs_MemberInterests] WHERE [memberid] = @memberid"

InsertCommand="INSERT INTO [gs_MemberInterests] ([memberid], [Interest]) VALUES (@memberid, @Interest)"

SelectCommand="SELECT memberid, Interest FROM gs_MemberInterests WHERE (memberid = @memberid) AND (Interest = @interest)">

<DeleteParameters>

<asp:Parameter Name="memberid" Type="Object" />

</DeleteParameters>

<SelectParameters>

<asp:SessionParameter Name="memberid" SessionField="currmember" Type="Object" />

<asp:SessionParameter Name="interest" SessionField="currinterest" />

</SelectParameters>

<InsertParameters>

<asp:Parameter Name="memberid" Type="Object" />

<asp:Parameter Name="Interest" Type="String" />

</InsertParameters>

</asp:SqlDataSource>

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