moving partitions

[J.L. Blom]

I have a peculiar problem with moving partitions. I have, many years ago 
made a boot partition of 100 MB as I thought that was more than enough. 
However, as ubuntu grows, the needed room on the boot partition has to 
be increased as well, resulting in the fact that it now requires > 74 MB 
and the old Linux uses at least 35 MB so I don´t have not enough space.
OK, I booted from an USB-stick, used gParted and shrank the adjoining 
partition.
The boot-partition is an primary partition, while the next partition, 
which I shrank, was the first partition on the extended partition. I 
ended with an unused partition of ~1 GB.
Than I wanted to let the boot-partition grow with 1 GB. But that didn´t 
work. Gparted wouldn´t do that.
Now I´m stuck. Can somebody explain why this primary partition won´t 
grow and how I can solve this problem?
Thanks in advance,
Joep