Little help (T_CONSTANT_ENCAPSED_STRING)

Hei again. Last question:
I have:
if (!isset("1".$image["ID"].".jpg")){ and get:
Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING :(

Can someone fix this for me? Thanks. - I already tried all versions (with "", ''), still can't fix.

You can't test to see if a .jpg image is set ...

You can check to see if the file exists though ...

if(file_exists("1".$image["ID"].".jpg")){
echo "Yes, the file exists.";
}
else{
echo "No, it does not exist.";
}