Value errors

[Notters]

Hi can some one please help with this one. I'm trying to get the difference in days of two dates now i know you can just subtact one from the other however some of the dates are now txt, ie product was expected on 01/01/2010 but is now discontinued. this brings up a value error... how can i get rid of this value error so columb L of the attached spred sheet only shows those where dates are subtracted from dates?

[pike]

you could use

=IF(ISERROR(J3-K3),"Stuff",J3-K3)

[DonkeyOte]

Given date values are numeric you can conduct a basic COUNT test to est. dates exist in both fields, eg:

=IF(COUNT(J2:K2)<2,"?",J2-K2)

change "?" to be whatever you want to appear in this incompatible rows.