Is it possible you already had 24 or 25 values in @{$cnt} and are now violating whatever the range check $cnt <= 25 was checking against? And would the program 'glimmer' know what you wanted to do with the added arguments? That is, how would it 'know' what " 800 800" meant? (You might want to check how to tell the program to use a new 'xoffset' value, if it can)

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I'm a pessimist about probabilities; I'm an optimist about possibilities.
Lewis Mumford