Size of the row/column overlapping

I face the following problem when executing unwrapping.
Regardless of the row/column overlapping size (e.g. 100) during the unwrapping
in the output window I get a line saying “WARNING: Tile overlap is small (may give bad results)”,
but the procedure finishes well.

On the other side when set number of tile rows/columns to 100 the there another message
*“tiles too small or overlap too large for given input” then the execution stops.

Any ideas how the resolve this?