Resolve FX015: Sign lost and FX020: Data lost error in SAP

I found a strange error when working with table control in ABAP. There are two similar errors :
- FX015: Sign lost
- FX020: Data lost

The solution to this problems (for me, not sure it will work at other condition) is to add _.___.___.___.___.___V or _.___,___V (don't ask me why) at Text or I/O Field attributes. Look at the picture below.



For the details you can read this post http://sap.ittoolbox.com/groups/technical-functional/sap-dev/table-control-problem-691410