Not able to update Macbook

[KALYAN23]

I am using a Macbook version OSX 10.5.6 and m trying to update to 10.5.7, but don't know due to some error I am not able to. When ever i try to update it I get this error message "You cannot install Mac OS X Update on this volume. This volume does not meet the requirements for this update".
And I am trying to update it directly from the Apple's website but still I am not able to. Please can some one help me out of this problem.?

[MrChris-]

Well according to the error message it looks like your computer doesn't meet the requirements. Can you please give a brief on which Mac are you using.? Have you done a System Update.? Do you know the version 10.5.6 which you specified is right? How much free space do u currently have on your computer.? And how many user are there on that computer, I mean the number of logins.

[KALYAN23]

I bought this Macbook in October 2008 and I don't remember its not Aluminum but just one before that. And i have checked the version in About this Mac it says 10.5.6. And according to software update it says there are no update. And I have 30 GB free space on my Hard Drive. I am not getting why there are no updates I doubt there is some issue with the version of my computer. I am actually confused, don't know what to do now.

[jesse]

Even I think there is some issue with the Information provided by Software Update. And About this Mac maybe reporting wrong information on System Version. Try a different way to check the System version which is go to System Preferences and select Startup Disk. That will show the OS installed on your computer. There is an option of Combo update which you can try, search on Apple's website for an update. And another option will be of try downloading the 10.5.8 version and check if gets downloaded properly without any problem. Then we can figure out the actual issue. See for Combo Update first.