[quote user="Jon Summers"]
2. Does cellName contain a valid String? Is it the name of something in your cell library?
[/quote]
This! Within UserForm_Initialize(), txtPointCell.Text is given a hard-coded cell name yet the library wasn't actually loaded which is what is causing the error. I had already checked the values in 1, 3 & 4 and it all checked out and I forgot the CreateCellElement2 requires the cellname to a valid cell in the loaded cell library. To prevent the error I will set txtPointCell.Text="" and add a cell browser button to ensure the cell is correctly chosen each time. Thanks for prompting what to check its all working as it should bar the rotation so I have a date with the VBA help on Matrix3d this evening!