When using clickTAG to add a destination clickthrough URL to an ad, is there a
limit to the length of the URL string or limits on characters?

Example code producing display problem:
<embed
src='http://wlbt.images.worldnow.com/ads/44141_AM.swf?clickTAG=http://www.bellso
uth.com/employment/car_caropp.htm' quality='best' bgcolor='#ffffff' width='300'
height='150' name='Bellsouth_flash_300_150-ct' align='middle'
allowScriptAccess='sameDomain' type='application/x-shockwave-flash'
pluginspage='http://www.macromedia.com/go/getflashplayer' />

Shortened destination URL seems to remedy:
<embed
src='http://wlbt.images.worldnow.com/ads/44141_AM.swf?clickTAG=http://www.bellso
uth.com/employment' quality='best' bgcolor='#ffffff' width='300' height='150'
name='Bellsouth_flash_300_150-ct' align='middle' allowScriptAccess='sameDomain'
type='application/x-shockwave-flash'
pluginspage='http://www.macromedia.com/go/getflashplayer' />

What's the issue here?