Custom line pattern splits when stretched..

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Hello
I've created a custom line pattern that scales ok up to about 4000 mm then it begins to split.
The line pattern look something like this =-= and used it looks like this =-==-==-==-=. After stretching it a bit it starts adding a gap like this =-= =-= =-= and as the line gets longer the gap widens. I've tried with the scaled parameter on/off but it has little effect.
Does anybody know why this happens and what I might do to fix the problem?

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Found out what causes the problem. Visio only supports 1000 instances of the custom pattern within each shape. Apparently this is a hardcoded limitation so I worked around the problem by creating a longer custom linetype.