Mpeg IMX 625/50 (30mb/s) Workflow in Final cut pro (field error)

Hey,
im new with the Mpeg IMX and i have few questions about it. I have two different workflows.

One
I get normal Mpeg files from Broadcasting switcher (Tricaster) i convert the clips with Mpeg streamclip to Mpeg IMX 625/50 (30mb/s). After that i edited them With Final cut pro 7 and export them out to MXF file conteiner. Everything is fine.

Two
I have music video on casette (Beta) I caputere it with Final cut pro as Dv pal anamorphic. I edit it in Final cut pro timeline. Then i copy the content (Music video) to Mpeg IMX 625/50 (30mb/s)project and export it out as MXF. Now the message i get from our broadcasting servise is that i might have field error on it? now i have tryed De-interlace filter but same thing i have tryed to change the field dominance but i does not help. And some times some files go throug?

Should i convert the captured video to IMX first and then edit it? the reason why i did not do it was because it adds one more step to my workflow and slows it down.

I have tryed to ask more details about the Field error but i have got none. They just mail that i might be the reason.