Variables in oData URL

I have searched high and low and have as yet come up with a solution to this issue I am having.

I am trying to crate a dataflow for an oData source. I have the URL to pull data from and it works fine but there is a PeriodStart and End date I need to supply. If I hard code the dates it works fine. I need this to be updated incremetally so I need to incormporate the RangeStart and RangeEnd paramerters into the URL so PBi can update incrementally as its a lot of historical data along with current data.

When I create a varable and format a date as it needs to be I can insert that into the URL using & RangeStart & and & RangeEnd & in the dataflow online via the Advanced editor and it works fine to bring up data in the preview table.

When I try to save the data flow I get an error:

Can't save dataflow

One or more tables references a dynamic data source.

It looks like a varable isn't allowed using OData.Feed. I have read you can use Web.Content as it will handle a varable without issue but I can't get that to work. The examples are a bit vague that I have seen.

If I paste the OData URL in a browser with a hard coded date I get back a normal XML responce with data.

Anyone have any suggestions on how I can acccomplish this? I've used Web.Content for API calls with variables just fine. Its just OData.Feed isnt programmed to handle variables.

TIA

Mike...