I haven't used the indent to make a mold cavity, normally I edit the part in the assembly, select Insert / Molds / Cavity. When the box pops up for the feature(s) to select for the cavity there is also a "Scaling" factor which supplies a similar result.
Hope this helps.
Thanks for your reply, I tried using the cavity feature, as it lets me select the assembly, however it gives me the error message "Rebuild Errors: Unable to create this feature because it would result in zero thickness geometry.
I think the part is a bit too complex. I has holes in it for screws and things to be put in later, but I can see how this would effect making a mold, as there would be solid 'bits' floating in mid air, and solidworks doesn't seem to like this.
The Zero thickness is something that crops up from time to time.
Check for holes that end up being tangent to the cavity.
It is possible that this is what is causing the indent operation to fail as well.
With the mold feature as well as cuts, if these operations result in separate entities floating around, a pop up box will let you keep or remove them.
Another issue which could be the size of the scaling with a radius intersecting itself.
I have not experienced complexity causing these problems.
As always, if you can post your models, some one will be able to show a fix.