SQL Bridge Historical Scan

Hi, I have a problem with SQL Bridge 5.3.4 and Vision Module 5.3.6
I have defined a Scan Class call “Production” with mode Direct - Analog Type and Scan Rate 5000ms but the tags doesn’t historicizes with the given frequency, some tags si but others do not.
More over, if I set up the Default Scan (real time) all the tags start to historicized but after a few minutes some tags stop their historicizing and I see the change of the tagvalue in the designer.