Could not add multiple data in Slicer's Data Field

Chibi-devil 

Hi there!

It sounds like you're facing a little hiccup with the slicer functionality in Power BI Desktop. Normally, when you add a date to a slicer, Power BI automatically gives you a hierarchy that lets you drill down from year to quarter to month, and so on. But it seems like that's not happening this time around. No worries though, we can try a couple of steps to troubleshoot this.

First off, let's make sure we're not missing something simple:

1. Hierarchy Slicer: When you drag your date field into the slicer, make sure to select the arrow next to the field to expand and see the hierarchy (Year > Quarter > Month > Day). Sometimes, it defaults to a single level.

2. Clear Slicer Selections: If there's any existing selection or filter within the slicer, try clearing it. This might reset any issues and allow you to add both Year and Month again.

If the basics look fine, let's try a more manual approach:

1. Create Custom Columns: In Power BI Desktop, you can create custom columns for the Year and Month. Here's how:
- Go to the "Transform Data" section by clicking "Transform Data" from the Home tab.
- In the Power Query Editor, select the date column, then under the "Add Column" tab, use the "Date" dropdown to add a "Year" and "Month" column.
- Once you've added these, go back to the report view, and you should be able to add these new columns to the slicer individually.

2. Create a Date Table: Sometimes, it helps to have a separate date table with unique Year and Month columns. You can create one in Power BI using DAX:
- Go to the Modeling tab and choose "New Table".
- Use the DAX formula to create a calendar table. Here’s a simple example:
```
DateTable = CALENDAR (DATE(2000,1,1), DATE(2025,12,31))
```
- Then add Year and Month columns to this new table.
- Define relationships between this date table and your data, and use the Year and Month columns from the date table in your slicer.

3. Check for Updates: Ensure your Power BI Desktop is up to date. Sometimes bugs are fixed in newer releases.

If after trying these steps the slicer still isn't behaving as expected, it could be a more unique issue related to the latest update or something specific in your Power BI file.

And of course, if you feel like you're going in circles, feel free to give a shout. Sometimes two heads are better than one, especially when it comes to puzzling out tech gremlins. Let's get that slicer sorted so you can get back to the fun part—digging into your data!