Most likely the thisform.txtdt.value does not contain the proper date.
Try to modify like:
clist1 = dtoc(iif(type("thisform.txtdt.value")="D",thisform.txtdt.value,{}))



>I use the following code to get the date value from txtdt.value text box.
>
>clist1 = dtoc(thisform.txtdt.value)
>
>this project is used in 4 different places.
>
>in two places they are getting error saying unrecognized keyword.
>
>other two places it works fine.
>
>will there be any problem with the old databases to recognize the key word dtoc.
>
>Thank you very much.