Symptoms

The investigation show that this is happening to the column with monetary values. A closer look indicates that the column is using thousand separator column. Disable that property allow the column to be sorted correctly.
 

Diagnoses

This is a known issue that was resolved in Smartforms 4.6.9
 

Resolution

The workaround is to disable Thousand Separator property. The fix for this issue already included in Smartforms 4.6.9