Display method not showing value in SSRS report

Two days struggling to make a simple display method in an SSRS report with no luck,

Here below the code I am using. The display method is discovered in the designer but shows no value when running the report.

Any clue how to fix this?

[ExtensionOf(tableStr(CustTable))]
public final class MyCustTable_Extension
{
[SysClientCacheDataMethodAttribute(true)]
public display Description test()
{
Description test;

test = 'test' ;

return test;
}

}