Issue with Parameter Fields

Hi keithjam,
Thanks for reaching out to the Microsoft fabric community forum.

In Power BI, implicit measures are automatically created when you drag a numeric column (like Sales Amount) into a visual, applying default aggregations such as SUM, AVERAGE, or COUNT. However, these cannot be used in certain scenarios, such as Field Parameters and SWITCH functions, because Power BI requires explicit calculations. This is where explicit measures come in manually defined using DAX, such as Total_Sales = SUM('Sales Table'[Sales Amount]). If you need an aggregated column in a field parameter, you must first create an explicit DAX measure (e.g., Total_E0x = SUM('Error Data'[E-0x])) instead of directly using the raw column. This ensures that Power BI can correctly interpret and apply the selected aggregation. Ultimately, explicit measures provide more control and flexibility, allowing dynamic switching between fields in visuals like line charts while avoiding errors.

Reference article for the above point: Use report readers to change visuals (preview) - Power BI | Microsoft Learn

Write a DAX query that first captures the slicer selection in a variable, then uses a SWITCH statement to dynamically sum the corresponding column (E-0x or E-2x) based on the slicer’s selection.

And then drag this measure to y-axis for the line chart, please try this method.

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Thanks and Regards