elseif in csh

I have been using the if statement in csh like this

if ( $opt1 == 1 ) then
 .....

elseif ( $opt2 == 1 ) then

......
endif

Seems to work, but got

Badly placed ()'s.

When I used a space in the elseif, a space between the 'else' and the 'if' it worked

if ( $opt1 == 1 ) then
 .....

else if ( $opt2 == 1 ) then

......
endif

Any idea why the thing sometimes works and sometimes not???