RDA LTRIM([RV String],'AZ-') returning weird results

hi all,

I am using the text function LTRIM to remove the first three characters from a string.  When I use LTRIM([RV String], 'AZ-') from a string AZ-123456 it is returning Z-1234.  The expected result should be 123456.   I removed all blanks from the string, and tested the length as well.  Can you advise what needs to be done to retrieve the expected result?

Thanks.