Changed radiator, now tranny won't shift into overdrive

Jnybob

Hi Folks, I removed my radiator, cleaned it, then re-installed. Now it seems my transmission won't shift into OD. The radiator has oil cooler lines, and transmission cooler lines. Could I have caused this problem when connecting the tranny cooler lines? Would air, or water in the lines be the cause of this problem? Thanks in advance for your help.
Jnybob

Mr_Shiftright

Did you recheck the fluid level in the transmission?