SSRS Formatting output

Frankly I'm frustrated by the formatting options available in SSRS when trying to get a field to look the way you want. The built in choices are good for a few things but it is tricky to get a custom one to work. I have gotten some to work but it is very hit or miss. My Solution is to use the Format() function as part of the expression. This gives the most options with the best resulst a documentation that can be found easily through google. The only gotcha so far is that it the formatting codes are case sensitive: =Format(Fields!MyDateField.Value,"MMM-yy") results in a lovely Jan-09 output "mmm-YY" gives an odd 00-YY