Offset Curve on surface cannot change distance

I have been trying to change amount, but it will not let me. It seems set to 1 unit. I change amount to .5 and try clicking in another box for it to accept my amount. Sometimes it tells me how many and I select 1 and it then resets distance to 1 MM (in my case)

Thanks, Randy

Software information

Software versions
Rhinoceros version: 5.0 Wenatchee 2014-05-20 (514)
OS X version: Version 10.9.3 (Build 13D65)


Hardware information

Computer hardware
Hardware model: iMac12,2
Processor: Intel Core i5-2500S CPU @ 2.70GHz
Memory: 20 GB
Architecture: Intel 64 bit

Video hardware
Graphics: AMD Radeon HD 6770M 512 MB
Memory: 512 MB
Screen size: 2560 x 1440, 1280 x 1024
Displays: iMac, BenQ T701

Third party kernel extensions
at.obdev.nke.LittleSnitch (4092)

USB devices
Staples: Relay UFD
Apple: Internal Memory Card Reader
Apple Computer, Inc.: IR Receiver
Apple Inc.: FaceTime HD Camera (Built-in)
Apple Inc.: Bluetooth USB Host Controller

Bluetooth devices
Apple: Apple Magic Mouse
Apple: Apple Wireless Keyboard

OpenGL information

OpenGL software
OpenGL version: 2.1 ATI-1.22.25
Render version: 2.1
Shading language: 1.20
Maximum texture size: 16384 x 16384
Z-buffer depth: 24 bits
Maximum viewport size: 16384 x 16384

Implementation settings
Use texture compression: No

Appearance settings
Antialiasing: None
Mip map filtering: None
Anisotropic filtering: None

There are two numerical entry fields on the OffsetCrvOnSrf command options dialog. The Number field is the number of curves to be generated. It probably should be labeled as “Number of curves” and will only accept whole numbers. To change the offset distance, enter that value into the Value field.