Is it possible to hide the value of a cell if the cell throws up an error
message such as #N/A.

I have a workbook in which I have a formula that will fill a specific cell
based on scores in another couple of cells. Because the cells are not filled
until assessments are graded the formula automatically inserts #N/A as the
formula conditions are not met. The specific formula is :

=IF(COUNTA(D7:E7)<2,"",IF(AND(ISNUMBER(O7),O7<43), "F",LOOKUP(C7,{43;50;65;75;85},{"PC";"P";"C";"D";" HD"})))

Cells D7 and E7 are where the grades end up from another worksheet. I dont
want the #N/A to appear as it makes the sheet appear untidy.

I have a similar situation in the other sheets where based on the formula:

=IF('DO NOT DELETE'!C384.99,"HD",IF('DO NOT DELETE'!C374.99,"D",IF('DO NOT
DELETE'!C364.99,"C",IF('DO NOT DELETE'!C349.99,"P",IF('DO NOT
DELETE'!C342.99,"PC",IF('DO NOT DELETE'!C3=0,"F"))))))

where this formula automatically assigns a fail grade to every student
automatically until I enter the grades received. I would much prefer the
sheet left the cell blanjk rather than put an F in the cell until it was
completed through the process of the formula assigning it through grades.

Is there some way of stopping this occurring until the cell is filled
correctly.

In both aspects I would prefer the cell remained empty to reduce the risk of
errors and to tidy up the appearance of the sheet esstially.

Thanks

Brian