Why Tracking Fails: The Importance of Validation
Spending thousands of dollars on a marketing campaign without testing your UTM links is like flying a plane blindfolded. A single typo, a missing question mark, or an omitted utm_source can cause Google Analytics 4 (GA4) to dump all your valuable ad traffic into the dreaded "(Direct) / (None)" or "Unassigned" buckets.
The Missing Source Error
According to Google's official documentation, utm_source is the only strictly mandatory parameter. If you add a campaign name but forget the source, analytics platforms will often ignore the entire tracking string.
The "?" vs "&" Mistake
A URL's query string must always start with a question mark (?). Subsequent parameters must be separated by an ampersand (&). A common human error is using `?` twice, which breaks the URL entirely.