Operator '+=' cannot be applied to operands of type 'ODataBatch'

[stevsharp]

I am trying to use the following code but it gaves me the following error
Operator '+=' cannot be applied to operands of type 'ODataBatch'

Any idea ?
Thanks

Spiros

Task<List> storageTask = null;

batch += c =>
{
storageTask = c.For()
.FindEntryAsync();

 return storageTask;

};