keep getting the "uninitialized constant Paperclip::Watermark::PaperclipCommandLineError" error

[K.M.]

hi, all,

 I am running rails 3.2.2 and paperclip 3.0.1. Operating system is ubuntu 11 and yes, imagemagick has been installed successfully.

I keep getting the "uninitialized constant Paperclip::Watermark::PaperclipCommandLineError" when I upload an image and it's to be watermarked.

 I have googled for this error but nothing seems to come up that would help.

 I have used paperclip 2.x.x with rails 2.3.8 to no such error in the past with another project.

 Does anyone know what is going wrong?

 Please help.

thank you :)

Gordon