MTD Calculation error: A circular dependency was detected: SalesTran[Column], SalesTran[SalesYTD], S

Hi,

Can anyone give me suggestion that why "A circular dependency was detected: SalesTran[Column], SalesTran[SalesYTD], SalesTran[Column]." this error I am getting while calculating MTD?

Function I am using is SalesMTD = CALCULATE(SUM(SalesTran[Amount]),DATESMTD('Calendar'[DateKey].[Date]))

Thanks,

Anupam