Variable names starting with a number

[verona]

I've been using a variable that I created and
initialized in an internal Basic script for a while with
no problems until today when I decided to try using the
"Set Variable" action. As long as my variable name
starts with a number, the OK button stays grayed out.

Are variable names starting with a number unsupported?
Is it possible for my variables named in this way
through Basic scripts cause any problems when running
tasks?

[Oleg]

This is traditional requirement. All programming languages requires that variable names begins from literal symbols:
a..z, A..Z and underline symbol ( _ )

You may name your variables like this:
_1MyVar
_2MyVar
etc.