Hello, 

I'm currently following the salesforce trailhead, and one of the items it says for me to do is create a PushTopic 
https://developer.salesforce.com/docs/atlas.en-us.api_streaming.meta/api_streaming/code_sample_java_create_pushtopic.htm

I put in the code it lists into the developer console,
PushTopic pushTopic = new PushTopic();
pushTopic.Name = 'InvoiceStatementUpdates';
pushTopic.Query = 'SELECT Id, Name, Status__c, Description__c FROM Invoice_Statement__c';
pushTopic.ApiVersion = 48.0;
pushTopic.NotifyForOperationCreate = true;
pushTopic.NotifyForOperationUpdate = true;
pushTopic.NotifyForOperationUndelete = true;
pushTopic.NotifyForOperationDelete = true;
pushTopic.NotifyForFields = 'Referenced';
insert pushTopic;

but I get Line: 10, Column: 1
System.DmlException: Insert failed. First exception on row 0; first error: INVALID_FIELD, Invalid ApiVersion: [ApiVersion]

Any advise?