Sequential numbering with prefix

I'm trying to add numbering to my drawing with a prefix followed by sequential numbers, for example: E03.01. I've searched the forums here and found this:

http://forums.autodesk.com/t5/autocad-lt-general-discussion/adding-numbers-sequentially/td-p/1155787

Not pretty but it works on AutoCAD LT2005 don't know about other versions cos deisel syntax has been changable but:

Stick this on a user defined button to set a prefix and number to start at:

^C^Csetenv PREFIX \; setvar USERI1;

And this on another to do the sequential thingy:

*^C^C-text;\;$M=$(getenv,PREFIX)$M=$(getvar,USERI1);setvar;USERI1;$(+,1,$(getvar,USERI1))

Setting PREFIX and USERI1 works fine but I can't seem to get the text placement to work properly. It seems to want to run thru the TEXT command and ignore the variable settings. I'm running LT 2014. Any help at all would be greatly appreciated, thanks.