Yahoo CEO Terry Semel has said his Panama ad-platform upgrade has had the major bugs worked out and fixed, Reuters reports. But some advertisers are still seeing significant problems, according to Marketing Pilgrim.

Jeremy Luebke at MarketingPilgrim recounts his experience of having all conversion tracking within Panama at first returning questionable data, then going blank completely. Luebke says when he contacted Panama support the problem was identified as a known issue but no estimate given about when it would be resolved.

That contrasts sharply with Semel's assertion that Panama is now working fine and primed for the growth that Yahoo is counting on. That growth isn't expected to begin appearing until the second quarter, which might be when all the bugs are truly worked out of the system.