The problem is probably Vectorworks. The error you experienced should have been trapped. The latest build does a better job at preventing this.
But, in any case, you cannot convert pasted graphics into symbols. You can however, import a DXF file and use the resulting graphics, excluding bitmaps and text, as a symbol.
Here's how to import a DXF and make it into a symbol using the Rosco effects projector as an example.
1) Download the Rosco_X24_CAD_Symbols from
http://www.rosco.com/lighting/x24_docs. ... n=lighting
2) Open a new plot and then choose File->Import->DXF...
3) Select the XFX PlanSymbol.dxf file and choose "Open"
4) From the DXF import options sheet select "mm" and click "OK"
5) 66 entites are imported. There is one grouped object and some small text entities.
6) You can use the grid and rulers to determine that the grouped object representing the fixture body is about 3 feet wide. According to the Rosco specs, the unit is 12"x14"
7) Select the grouped object and choose Format->Transform->Scale...
Scale the object by 33% in both dimensions
9) The default direction for a symbol is for it to be pointing to the right. Use the Inspector to rotate the object -90 degrees.
10) Select Format->Convert->Selection to Path (Grouped objects cannot be directly made into symbols).
11) Select Format->Convert->Selection to Symbol
12) Choose the kind of symbol. Depending on if you are using DMX control or not, this would be either a fixed focus ERS or Automated Fixture. The Automated fixture kind has info for parameters like pan/tilt/zoom that you won't need. But, it allows you to enter sub-channels in the device info panel.
13) Enter other information such as the name, and beam. If you selected Automated Fixture, you would enter the same Beam/Field values for both wide and tight depending on the lens you selected. And, do likewise with candela wide and tight because there is no zoom for this fixture. You can ignore other extra information like pan, tilt and iris%.
14) If you selected Automated Fixture then you need to use the Device Info panel to add the appropriate DMX Addresses. Most of these you will enter text and LXBeams will select the next highest undefined sub-channel number. The dowser corresponds to Intensity which can be selected from the defined sub-channels popup. Sub-channel numbers below 50 are reserved for defined uses that are standard for LXSeries. Examples are Intensity, pan and tilt. Subchannel numbers 50-99 are open for use for functions particular to a given fixture. Martin fixtures in particular have DMX addresses that have multiple functions and there is no standard way defined to codify these at this time.
15) If you are going to create key entries for the different lenses, you might wish to use the default mark to distinguish between them.
16) You can remove other entries from the key and export it. Or, simply draw one of the new symbols and copy and paste it into another plot to use it.