Dynamic SQL with Dynamic xpath variable

[P Rike]

I have a loop that I am using to populate a variable with an xpath.

@xpath = concat('/record[',i,']/firstName');

I then have a variable I used to populate my sql statement.

@sql = 'select @value:=EXTRACTVALUE(xml,@xpath)';

then I use this statement to call the dynamic SQL.

PREPARE dynamic_statement1 FROM @valuesql;
EXECUTE dynamic_statement1;
DEALLOCATE PREPARE dynamic_statement1;

What is weird is it works some of the time and sometimes not and I can't find a pattern. I know my xpath is correct because if I just run this with the static xpath it returns a value.

SELECT @value:=EXTRACTVALUE(XML,'/record[1]/firstName');

Any ideas?