Query returns empty

Quick check

1. Does data exist? ProductData | take 100.
2. Is a filter too tight? Remove where clauses one at a time.
3. Are field names right? KQL is case-sensitive.

Step by step

1. Start simplest - ProductData | take 100. Returns rows? The issue is your filters. Nothing? Check the connection (No data showing).

2. Widen the window - ProductData | where Timestamp > ago(7d) | take 100. Start a week wide, then narrow once you find data.

3. Verify field names - ProductData | take 1 | project * shows the exact names.

4. Add filters one at a time

ProductData | count
ProductData | where Campaign == "spring" | count
ProductData | where Campaign == "spring" | where Signups > 100 | count

When the count drops to zero, you've found the filter at fault.

Debugging tips

| where Status =~ "active"            // case-insensitive
| where isnotnull(Signups)            // exclude nulls
| where Message contains "error"      // contains instead of exact

Paste the query to Azi and describe what you expected - it proposes the next debugging step. See KQL Basics.