The dimension tool will automatically create an angle dimension if you select two sketch line entities that are not parallel.
A couple of suggestions:
- Try using the ESC key to deselect everything prior to selecting the Dimension command. My thought is that you may be inadvertently pre-selecting sketch geometry.
- If you are dimensioning between two lines, try adding a parallel constraint between the lines prior to creating the dimension.
- Try different selections, like dimensioning from a point to a line instead of line to line.
I hope this helps. Please let me know if you have any questions.
If this doesn't help, is there any chance you could Autodesk Screencast to record the behavior you're seeing? This may help us to troubleshoot the issue.
Thanks,
Nathan Chandler
Principal Specialist