Iam programming in ASP.NET for my company's MSCRM. I use MSAPI to retrieve
and update field values in MSCRM. Iam able to do it with ease by programming
in VB.NET with the MSCRM object library.

Eg.

strUpdateXml = "<account><name>Steve
Langer</name><owninguser>{19838938-705A-4AB9-BC2E-2EDD88035EE5}</owninguser>
</account>"

CRMAccount.Update(UserAuth, RECID, strUpdateXml)

It works fine for the normal MSCRM fields

LATER, I created USERDEFINED fields in MSCRM. ( with the Deployment Manager
and published). The new field created can been seen in the MSCRM screen.
Customization is correct.

When I try to program with the USERDEFINED fields, the program fails with
the message.

"80041103The specified attribute does not exist on this entity.The attribute
'cfstestfield' is not an attribute of the entity
'Account'd:\mscrm\build\3017\src\platform\include\ omcore\CrmPropertyBagUtil.
inl418"

The code is:
strUpdateXml = "<account><cfstestfield>hello world</cfstestfield><name>Steve
Langer</name><owninguser>{19838938-705A-4AB9-BC2E-2EDD88035EE5}</owninguser>
</account>"

CRMAccount.Update(UserAuth, RECID, strUpdateXml)

Why is the code failing. Please help me with ideas.

Thanks,
Anand Sagar.