Paragraph Numbering Style/Formatting Issue

I have a document at the moment that has 3 different types of list in it, numbered, alphabetical and Roman Numerals.

I started with the numbered list using <n=1>.\t and <n+>.\t , this worked fine 1 through 5.

I then did an alphabetical list it just started from 'f', I forced this to restarted using <a=1>.\t and <a+>.\t to rectify this and it did 'a' to 'c' fine.

But then when I start the numbers again using <n+>.\t it has started at 4, not carried on from the last numbering as 6.

What am I missing here that will make it follow on from the old numbers?

Reluctant to force restart from set numbers because that defeats the purpose of having these styles and would have to do it many more times.