Upgrading Disk Space (Unit C:) in Guest OS Windows NT

Hi,

I´m trying to upgrade Disk Space in a VM Windows NT, Actual configured Space 4Gb, I want to add 2Gb (For a total of 6Gb).

No problem asigning space in VSphere, but when trying to add it with Windows Disk Administrator to the existing Partition, I can´t extend it (Unit C:)

In Disk Administrator you can watch the Space (2055MB) prepared but not able to extend the existing partition.

How can I extend the partition? Is there any application capable to do this? Am i doing something wrong?

Thanks in advance