ArcGIS 10: Label Expression - The expression contains an error. How to solve it?

[ScottChang]

Hi all,

I have the following VB script:
Function FindLabel ( [FtMcNair7Pts-Edit31Oct2011.Benzene]) if
( [FtMcNair7Pts-Edit31Oct2011.Benzene] >100) then
FindLabel = ( [FtMcNair7Pts-Edit31Oct2011.Benzene])
end if
End Function 

When I tested it, I got the following error:  The expression contains an error. Modify the expression and try again.
I have no ideas how to solve this error.  Please help and advise me how to solve this error.

Thanks,
Scott Chang

[ScottChang]

Attribute Table is attached here:

[MarkFawkes]

?Should the expession be [field name] (i.e. benzene) rather than [MXD name.field name] ?