[1.95b][SSP] Unable to use seed bags on crop blocks.

The issue is simple, occasionally I will receive seed bags from my crops which cannot be used on crop blocks. I am still attempting to discern a course of action which would allow this bug to be repeatable, but it seems rather random, though often coincident with retrieved crop blocks not stacking together.

Edit: New development! Placing one of these non-stacking crop blocks in a chest causes the Minecraft client to hang! No error log is generated nor displayed.

All the conditions required to plant the crops have been met, else wise I would not have brought this up.

Edit: I went ahead and checked other crops that had allowed me to plant successfully, and found that they did not meet the declared requirements for planting. Upon fixing those problems, the original crops with which I was having issues allowed me to plant my crops.

Conclusion: It looks like the planting requirements are being checked, but the locations of those requirements are not being checked correctly.