There can be various reasons for such issue:

– Your traffic source has many/slow redirects (e.g: there are a lot of their internal redirects before the visitor actually is redirected to your tracking URL, as a result – he quits the page before the click comes to RedTrack).
– Different time zones in RedTrack and traffic source.
– Your traffic source has bot traffic (bots may not wait for the page loading and as a result, not all the clicks are registered in RedTrack).
– etc.

RedTrack records all the data it receives and clicks are not an exception. Unfortunately, we do not control the clicks amount in your traffic source and cannot provide the reason for such discrepancy on their side. What can be done:
1. Check your time zones in RedTrack and traffic source as they may differ significantly and cause the discrepancy. If this is not the case, proceed with step 2.
2. We suggest you take your clicks-report from RedTrack (it is available all the time and can be shared if needed) and ask your traffic source account manager for advice: Logs-> Clicks-> Choose the time period-> Export