Getting circle with line through it

[Nikilet]

I have two computers with Windows 10 Home on both, Thunderbird on both, and Smileycons program on both. I have checked permissions on both programs/both computers and they are the same.

One one computer I can move the icons to my emails and on the other computer I get a circle with a line through it and icons won't transfer.

Does anyone know what could be causing this?

 

[Bighorn]

Usually the circle with a diagonal line means the operation can't be done, about the same as a traffic sign that means No Entry on One-way streets or On Ramps. One of the Thunderbird must have an entry in Options or Preferences that is preventing it.

 

[Nikilet]

I have no idea what happened. The only thing I did extra was run a program I have called Reg Organizer. I can now use my Smileycons on the offending computer! Thanks for responding though.