if statement formula

[skatmandu2002]

Okay, i need to write a quite simple formula, but for some reason I just can't get my head round it.
However, to explain the background to my spreadsheet may be a little complex, I'll try my best...

One part of my spreadsheet is a simple table. There are ten rows (placements 1-10) and the columns are as follows:
- PLACEMENT NUMBER: Placements 1-10
- PLACEMENT NAME: The names of the ten placements are automatically inserted from another part of the workbook where the user types the placement name. If the user has not put in the placement name, 'N/A' appears in this column.
- COMPLETED?: This checks the date that placement is due to finish (inserted by user in another part of workbook) and sees if it is before todays date. If it is, a 'YES' appears for that placement in this column. If not, an 'NO' appears.
- HOURS REQUIRED: This takes the number of hours required (inserted by user in another part of workbook) for this placement.
- HOURS ACHIEVED: This takes the number of hours achieved (inserted by user in another part of workbook) for this placement.
- HOUR DIFFERENCE: this works out the absolute difference between the required and achieved hours
- UP/DOWN: If the difference between achieved and required hours means I am down on my hours, and 'DOWN' appears. an 'UP' appears if I am up on hours.

All the above is already programmed without problem. And there is also conditional formatting so that if the placement is not completed, the text in the last four columns disappears to prevent any weird figures from displaying.

Now, here's what I need to do...

I have a separate column which will be hidden when I'm done. This column will be entitled 'ERROR?'. What I want this column to do is:
- IF THE PLACEMENT IS NOT COMPLETED: then 'No error' to appear
- IF THE PLACEMENT IS COMPLETED: then I want the cell to check if a) the placement name says 'N/A', and b) if the achieved hours say '0'. If EITHER of these are true, then this column should read 'Error'. If not, then the column should read 'No error'.

I need to do this because I have a separate cell that says nothing if ALL the 'ERROR?' column says 'No error'. But if any of the placements show an 'Error', this cell will tell the user to insert all details for completed placement(s). I have already worked out a formula for this, I'm just having difficulty making the formula for the 'ERROR?' column.

If anyone could help, that would be great!

Thank you