PickFromQueue not working

POST /api/data/v9.0/queueitems(76d85f5f-9770-e811-a964-000d3ab6eb93)/Microsoft.Dynamics.CRM.PickFromQueue HTTP/1.1

{"entity":{"@odata.type":"Microsoft.Dynamics.CRM.queueitem","queueitemid":"76d85f5f-9770-e811-a964-000d3ab6eb93"},"SystemUser":{"systemuserid":"1C3BED0C-1114-495E-8FA2-B9E30D5CEFFE","@odata.type":"Microsoft.Dynamics.CRM.systemuser"},"RemoveQueueItem":"false"}



The error message is 

"error": {
"code": "0x8006088a",
"message": "')' or ',' expected at position 8 in '(76d85f5f-9770-e811-a964-000d3ab6eb93)'.",
"innererror": {
"message": "')' or ',' expected at position 8 in '(76d85f5f-9770-e811-a964-000d3ab6eb93)'.",
"type": "Microsoft.OData.ODataException",
"stacktrace": " at Microsoft.OData.UriParser.FunctionCallParser.ParseArgumentListOrEntityKeyList()\r\n at Microsoft.OData