Special linetypes don't seem to be visible in Paper Space or plotting correctly.
First try using the LTSCALE/PSLTSCALE and REGEN commands. If these commands do not solve the problem, you can assume that it's not a linetype issue. Instead, the zigs and zags are just not there – not even in the preview.
You can then go to the Layers dialog box to attempt to reload the linetype. If you receive a series of error messages, there's a good chance that a corrupt or incorrect version of the standard AutoCAD support file, LTYPESHP.SHX, has been loaded.
You can then try the LOAD command.
If this step doesn't work, you'll need to obtain the linetype file from someone else.
Here's a link to a forum thread discussing this issue.