OData data error Syntax error '$' at position 4.

Hi there,

I'm using OData to get phone number on Task screen. Its working fine but suddenly it showing an error. I did not understand why now this error occur because thousands of Tasks created against the records.

Server: MSD CRM 2013 On-Pre.

Error message:

Syntax error '$' at position 4.

Odata query:

http://mycrmserver/myorg/XRMServices/2011/OrganizationData.svc/AccountSet?$select=Telephone1$filter=AccountId%20eq%20guid'%7xxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx%7D'

If I remove $select=Telephone1 then its working fine.

Please Suggest.