Compare date in cell against dates in range of cells

Hello,

I am trying to use conditional formatting to highlight a cell if the date in that cell is the same or earlier than dates in the rest of the row. The problem is that some of the cells do not have dates in so are blank or they contain text.

A1 is the expected completion date. The rest of the columns are populated with action dates or text and I would like to quickly see if an action date has been given which is on or after the completion date. I can get this to work on rows that do not contain text but not where cells contain text.

Is this possible? Thanks in advance for your help. I am using Excel 2003.