TypeError-Cannot cast array data from dtype('O') to dtype('float64') according to the rule 'safe'

Question

I have plotted two plots on the same axis using twinx() but the output isn't correct. The plots are not aligned with respect to zero axis. I am sharing the plot below.

Days percentage change is float and total traded quantityis integer.

fig = plt.figure()
ax1 = fig.add_subplot(1, 1, 1)
ax2 = ax1.twinx()

ax1.set_xlabel('Date')
ax2.set_ylabel('Total Traded Quantity', color='red')
ax2.plot(df['Total Traded Quantity'], 'r-')

ax1.plot(df['Day_Perc_Change'], 'b-')
ax1.set_ylabel('Day_Perc_Change', color='blue')


def align_yaxis(ax1, v1, ax2, v2):
    y1 = ax1.transData.transform((0, v1))
    y2 = ax2.transData.transform((0, v2))
    inv = ax2.transData.inverted()
    dy = inv.transform((0, 0)) - inv.transform((0, y1-y2))
    mini, maxi = ax2.get_ylim()
    ax2.set_ylim(mini+dy, maxi+dy)
align_yaxis(ax1, 0, ax2, 0)

I'm also getting a typeError-Cannot cast array data from dtype('O') to dtype('float64') according to the rule 'safe'. Please help if you can fix it and align the axis for proper visualization.