Why is the global sourcetype defined in props.conf and transforms.conf not used by my custom app?

Hi guys I've defined my sourcetype, transforms and lookup in /opt/splunk/etc/system/local/props.conf and /opt/splunk/etc/system/local/transforms.conf (I set the lookup from the web interface). Everything is working fine with the default Search and Reporting App. After I created my customApp and if I perform the same search in the App, I can see the right source_type associated to my data but the regex that I defined in /opt/splunk/etc/system/local/transforms.conf is not applied. Any suggestion? Thanks