Caml Query Help

[sheldons]

HEEEEEEELP! I am executing this as an async query with the the following caml below. I keep getting an error returned.

<View>
<FieldRef Name='myID' />
<FieldRef Name='ContentType' />
<FieldRef Name='DocName' />
<FieldRef Name='myFirstName' />
<FieldRef Name='myLastName' />
<Query>
<Where>
<And>
<In>
<FieldRef Name='ContentType' />
<Values>
<Value Type='Text'>CT1</Value>
<Value Type='Text'>CT2</Value>
<Value Type='Text'>CT3</Value>
<Value Type='Text'>CT3</Value>
</Values>
</In>
<Eq>
<FieldRef Name='myID' />
<Value Type='Text'>{0}</Value>
</Eq>
<IsNull>
<FieldRef Name='AnotherID'></FieldRef>
</IsNull>
</And>
</Where>
</Query>
</View>

Below is the message and exception that I am getting back. Message: "Cannot complete this action.\n\nPlease try again." Exception: {Microsoft.SharePoint.Client.ServerException: Cannot complete this action. Please try again. at Microsoft.SharePoint.Client.ClientRequest.ProcessResponseStream(Stream responseStream) at Microsoft.SharePoint.Client.ClientRequest.ProcessResponse(HttpWebResponse response) at Microsoft.SharePoint.Client.ClientRequest.ExecuteQueryGetResponseAsyncCallback(IAsyncResult asyncResult)} I need help with this asap to solve a production issue.

[sheldons]

To build further on this. The problem I am having is with the following:

<IsNull>
<FieldRef Name='AnotherID'></FieldRef>
</IsNull>