Newbe question at ASP and web deployment

I have my club site up and running using SQL hosted by 3rd party. Now trying to improve the login / new user process.
I have it set that the new user default "isapproved" field is false.  Now trying to create a page for admin users to access this data and update this info.
I have a grid view tieing in directly to the aspnet_Membership table, data shows fine in the browser. When I hit the edit, I can change the data, when I hit update, i get an error.

The issue is not just with this field and table, if I change the source data to another table, ie: "memberinfo" and try to update the phone field, I get the same issue.
I can update the field manually by opening the table directly in Database Explorer. Just not via a web page .

Can someone please assist and point me in the right direction as to where I need to look to solve this issue. 
Thanks in advance

K

If you want a ready-made drop-in package to manage users for the club site, check out http://www.aspsksolutions.com.  Note that there is a small fee for the package (I don't think he can quit his day job).

The package has quite a few options.  I use email verification, which causes an email to be sent to anyone who registers with the site.  They have to click on a link in the email to complete the registration.  That ensures that I have a valid email address for all registered users.

He also has a nice bulk-emailer package that I like.

Note that I have no connection to aspsksolutions other than as a satisfied customer.

There are a few bugs in the package, but fixes and/or work-arounds are posted in his forums.