Adding IFERROR to functioning formula and getting INVALID DATA TYPE

BFuller

Hello,

I currently have this formula and it works perfectly:

=IFERROR(NETWORKDAYS([PCD Draft 1 Start Date]@row, [Completed Date]@row, {Holidays}), "")

I need to include in this formula two columns for projects that are on hold (internal hold and external hold). Those columns have a formula in them looking at the networkdays between hold start date and hold end date. When a project is complete, I want to know the total days it was in active status (from start date to complete date, minus any hold days).

This formula seems to be working, but when I add the IFERROR portion, Smartsheet tells me it's "not quite right". Can someone help me?

This seems to work, but on projects that aren't yet completed I get INVALID DATA TYPE.

=(NETWORKDAYS([PCD Draft 1 Start Date]@row, [Completed Date]@row, {Holidays}) - SUM([Internal On Hold End Date]@row:[Total Hold Days]@row))

I want to include the IFERROR rule in this formula, but I've got something wrong:

=IFERROR(NETWORKDAYS([PCD Draft 1 Start Date]@row, [Completed Date]@row, {Holidays}), "" - SUM([Internal On Hold End Date]@row:[Total Hold Days]@row))

Can someone help?